I get the picture that this sfrm_Persons_Attending is the name of your subform. In that case, the syntax is incorrect and Access thinks you're referring to a field. Try
[Forms]![Main form name]![subform control name].[Form]![control name on subform] where subformcontrol name is the name of the control that contains the subform. It is not the subform itself. One other difference is that you have !Form and not .Form. This is about the best explanation of the use of the operators that I've come across http://bytecomb.com/the-bang-exclama...erator-in-vba/
Note that you don't need .Value for combos or text boxes as it's the default property. All that being said, it's worth noting that the form you want to pull these values from has to be open at the time. If it cannot be (or even if it can be) sometimes it's easier to pass values to an opening form via the OpenArgs property of the DoCmd.Open method. I also think the statement that the subform 'lives' on the form and not the tab control itself is correct, so I don't see including the tab control in the expression that references the control you want to access.
Last edited by Micron; 11-13-2017 at 02:27 PM.
Reason: spelin
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.