Referring a screen field from a tab

Dear all,

I am trying to get a field value in Project Navigator/Work Orders/Active Work Orders tab. When I refer a field in the same tab:

:i_hWndFrame.tbwWorkOrder_Cust.colWoNo it works properly.

However, I am trying to use a field that is located at a parent tab when I am in the same Active Work Orders tab and it does not work. Por example:

:i_hWndFrame.frmProjectInfoNew.cmbsProjId does not work or

i_hWndParent.frmProjectInfoNew.cmbsProjId does not work either.

Anyone knows how to refer to fields in a parent tab from a child tab.

I appreciate

Thanks