Cascading Combo Box in Subform, parameter error

[halnurse]

I have limited knowledge of access and I am self taught so be gentle. Anyway, here is my issue. I have a form (frmPS_Entry) that has a cascading combo box (one combo box filters one another). FrmPS_Entry works properly until I try to put it in frmReceiving as a sub form. When I try to use the sub form it gives me a "Enter Parameter Value" error. The first combo box selects the purchase order number and is sourced from a table called tblPS_Entry. The second is supposed to then only show material from that purchase order rather than all of the material ever entered. This combo box is sourced from a table called tblMaterial_Tracking. I did some research and currently this is how I have it set up: the PO_Number combo re-queries after update and then the Material combo box I went into the "Row Source" in properties and added a criteria [Forms]![frmPS_E]![PO_Number]. Let me know what other information you need. Please advise on how I could fix this issue or where I have gone wrong, thanks for your time.

[CJ_London]

see this link about how to reference objects from different locations

http://access.mvps.org/access/forms/frm0031.htm

basically your subform is not 'visible' outside of the main form, so you need to refer to the main form, then the subform control then its' source object and finally the control name on that subform - so perhaps something like

[Forms]![frmPS_Entry]!subformcontrolname!form![PO_Number]

however there may be a shortcut if you look at the link

[halnurse]

Thank you for your fast reply. It seems that worked!!