Invalid form number reference (application or object defined error)

[Lars Brownies]

I'm trying to push form A's button from form B, like this:
Call Forms.FormA.btnQS_Click

It worked before on several other forms.

Now I'm getting the error: 2456 Invalid form number reference.
I can't see what I'm doing wrong, since I use the exact same button name.
Any idea's?

Thanks,
Lars

 

[Lars Brownies]

Never mind. I found it.
The button that is called has to have a public sub.

Lars