Run time error: is null or not an object

I had 2 forms (frmMain,$$View Template for vMain), and 1 view (vMain). frmMain had a field(bName) that should match with vMain fist column (ID). So when I click the action button in frmMain to open the $$View Template for vMain, “run time error: document.forms[0].field1.value is null or not an object”. Anybody know why this happend?

The command I used in Action button is:

@URLOpen(@WebDbName + “/vMain/” + bName + “?opendocument”)

Subject: RE: run time error: is null or not an object

This is a JavaScript error. Please describe the sequence of events in greater detail. Does the new window open before this message appears? Does it really say “field1”? Do any of your forms contain a field named “field1”? Do you have passthru HTML on either form that includes a tag?