auto Data merge

Hallo,

I hope someone can help me? I want to have a JavaScript (eventually vbs) that auto generates a new merged document. If I play the script, Step 1,2 & 4 works. But the most important, step 3, doesnt work. I hope, someone can give the correct code. Thanks!

//OpenDocument.jsx
//An InDesign CS3 JavaScript
//Step1, Opens the document.
var birthDaycard = app.open(File("/c/document/birthday.indd"));
//Step2, Select data
var dmg = birthDaycard.dataMergeProperties;
dmg.selectDataSource(File("/c/document/birthday.txt"));

//Step3, create merged document
var dmd = verKaart.dataMergeOptions;
dmd.createNewDocument;

//Step4, ready
alert ('Done!');