Java script to send email not working when using Adobe Reader

Hope someone can help with my issue. I have a simple script attached to a button that I created using Adobe Pro DC. The Submit button has a script that sends the form to an email address specified in one of the forms fields (field is called ClientEmail). It all works fine in Adobe Pro DC but when I try and run the form in Adobe Reader XI, the following error pops up in the Java Script Debugger box when clicking on the Submit button:

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JAVA SCRIPT DEBUGGER

Acrobat EScript Built-in Functions Version 11.0

Acrobat SOAP 11.0

GeneralError: Operation failed.

Doc.mailDoc:20:Field Submit:Mouse Up

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This is the Java Script I have attached to the submit button:

Action = Mouse Up

Select Action = Run a JavaScript

The script is as follows:

var cToAddr = this.getField("ClientEmail").value;

var cSubLine = "This is the subject line - test"

var cBody = "Test message body."

this.mailDoc({bUI: true, cTo: cToAddr, cSubject: cSubLine, cMsg: cBody});