One Subform to another Subform

I have multiple subforms on one form. Through a click event on one subform, I am tyring to set the value (via dlookup) of a textbox in another subform. Problem is that I cannot seem to get Access to properly recognize the referenced subform & subsequent control on the sub. Through this site, I came up with the following but I still get a runtime error:

Forms!formname!subformname.Form.controlname

Help me obiwon

Thanks