populate form fields through Javascript

Hi,

the script below works fine when I run it from the console in Adobe Acrobat DC.

var v = this.getField("A0-Name1");
var myDoc = app.openDoc({cPath: "/C/UserData/user/Documents/A1-template.pdf", bHidden: false});
myDoc.getField("A1-Name1").value = v.value;

However when I trigger it through a button I get the Error:

TypeError: myDoc is undefined

3:AcroForm:A1button:Annot1:MouseUp:Action1

any Ideas?

thanks!