Unable to get column in spreadsheet

Hi, I am using RPA express 2.0.1
I try to get the 4th column values into a list variable. But I get an error

Error executing GetColumnAction
com.workfusion.studio.rpa.recorder.playback.PlaybackMultiException: Error executing TemplateAction[templateName=GetColumnAction.ftl,id=3,name=Optional[GetColumnAction],parent=1,arguments=ActionArguments[varName=[so],delay=[0],xsi:type=[recorder:GetColumnAction, recorder:GetColumnAction],pollingInterval=[300],active=[true],OpenSpreadsheetAction_filePath=[C:\Users\CHLOZHAO\OneDrive - Schenker AG\Desktop\Copy of Cisco mHub Shipment Tracking-2018.xlsx],actionDetails=[(3)],idx=[3],useIdx=[true],awaitTimeout=[5000]]]
at com.workfusion.studio.rpa.recorder.playback.action.OpenSpreadsheetAction.execute(OpenSpreadsheetAction.java:52)
at com.workfusion.studio.rpa.recorder.playback.action.OpenSpreadsheetAction.execute(OpenSpreadsheetAction.java:16)
at com.workfusion.studio.rpa.recorder.playback.player.ActionPlayer.next(ActionPlayer.java:53)
at com.workfusion.studio.rpa.recorder.player.PlaybackLogic.playNextAction(PlaybackLogic.java:153)
at com.workfusion.studio.rpa.recorder.player.PlaybackLogic.run(PlaybackLogic.java:113)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.openqa.selenium.WebDriverException: Failed to execute script. Cell index must be >= 0
Build info: version: ‘9.0.0.3’, revision: ‘1610cb545e’, time: ‘2018-05-24T16:45:36.185Z’
System info: host: ‘DESKTOP-C0PA3PJ’, ip: ‘10.215.6.174’, os.name: ‘Windows 10’, os.arch: ‘amd64’, os.version: ‘10.0’, java.version: ‘1.8.0_121’
Driver info: driver.version: UniversalDriver
Command duration or timeout: 0 milliseconds
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.openqa.selenium.remote.ErrorHandler.createThrowable(ErrorHandler.java:216)
at org.openqa.selenium.remote.ErrorHandler.throwIfResponseFailed(ErrorHandler.java:168)
at org.openqa.selenium.remote.http.JsonHttpResponseCodec.reconstructValue(JsonHttpResponseCodec.java:41)
at org.openqa.selenium.remote.http.AbstractHttpResponseCodec.decode(AbstractHttpResponseCodec.java:82)
at org.openqa.selenium.remote.http.AbstractHttpResponseCodec.decode(AbstractHttpResponseCodec.java:45)
at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:164)
at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:656)
at org.openqa.selenium.remote.RemoteWebDriver.executeScript(RemoteWebDriver.java:592)
at com.workfusion.rpa.helpers.RPA.executeScript(RPA.java:864)
at com.workfusion.rpa.helpers.RPA.executeGroovyScript(RPA.java:930)
at com.workfusion.rpa.helpers.Excel.getColumn(Excel.java:319)
at com.workfusion.rpa.helpers.Excel$getColumn$0.callStatic(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallStatic(CallSiteArray.java:56)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:194)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:214)
at Script4.run(Script4.groovy:6)
at com.workfusion.studio.rpa.recorder.playback.shell.GroovyShellWrapper.executeScript(GroovyShellWrapper.java:90)
at com.workfusion.studio.rpa.recorder.playback.player.PlaybackContext.executeScript(PlaybackContext.java:65)
at com.workfusion.studio.rpa.recorder.playback.action.template.TemplateAction.executeBehavior(TemplateAction.java:35)
at com.workfusion.studio.rpa.recorder.playback.flow.StandardControlFlow.execute(StandardControlFlow.java:46)
at com.workfusion.studio.rpa.recorder.playback.action.template.TemplateAction.execute(TemplateAction.java:30)
at com.workfusion.studio.rpa.recorder.playback.action.template.TemplateAction.execute(TemplateAction.java:17)
at com.workfusion.studio.rpa.recorder.playback.player.ActionPlayer.next(ActionPlayer.java:53)
at com.workfusion.studio.rpa.recorder.player.PlaybackLogic.playNextAction(PlaybackLogic.java:153)
at com.workfusion.studio.rpa.recorder.player.PlaybackLogic.run(PlaybackLogic.java:113)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.openqa.selenium.WebDriverException: Failed to execute script. Cell index must be >= 0
Build info: version: ‘9.0.0.3’, revision: ‘1610cb545e’, time: ‘2018-05-24T16:45:36.185Z’
System info: host: ‘DESKTOP-C0PA3PJ’, ip: ‘10.215.6.174’, os.name: ‘Windows 10’, os.arch: ‘amd64’, os.version: ‘10.0’, java.version: ‘1.8.0_121’
Driver info: driver.version: UniversalDriver
Build info: version: ‘9.0.0.3’, revision: ‘1610cb545e’, time: ‘2018-05-24T16:45:36.185Z’
System info: host: ‘DESKTOP-C0PA3PJ’, ip: ‘10.215.6.174’, os.name: ‘Windows 10’, os.arch: ‘amd64’, os.version: ‘10.0’, java.version: ‘1.8.0_121’
Driver info: driver.version: UniversalDriver
at com.workfusion.autoit.driver.AutoItDriver.executeScript(AutoItDriver.java:189)
at com.workfusion.universal.driver.UniversalDriver.executeScript(UniversalDriver.java:149)
at org.openqa.selenium.remote.server.handler.ExecuteScript.call(ExecuteScript.java:54)
at org.openqa.selenium.remote.server.handler.WebDriverHandler.handle(WebDriverHandler.java:41)
at org.openqa.selenium.remote.server.rest.ResultConfig.handle(ResultConfig.java:133)
at org.openqa.selenium.remote.server.JsonHttpCommandHandler.handleRequest(JsonHttpCommandHandler.java:203)
at org.openqa.selenium.remote.server.InMemorySession.execute(InMemorySession.java:98)
at org.openqa.selenium.remote.server.WebDriverServlet.lambda$handle$0(WebDriverServlet.java:231)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

@chloe_zhaoatUp you need to define the column index with a letter, not a number