Why won't this form release?

Have a form class in a vcx with a close button with 'release thisform' or 'thisform.release()' in the click method.

In another form have a button with this in the click method:

local oForm
oForm=newobject('frmMyFormClass','myClassLibrary.vcx')
oForm.show(1)

Clicking on the close button on the myFormClass form does not release the form! I have to click on the 'X' in the titlebar to close the form. Why is that? If this is unstandard code, how would I lauch a form that exists only as a class?