Have you tried setting the RowSource property of the combo boxes?
Prior to doing
frmCriteria.Show
you should run some code to set the RowSource properties. The best way is to use the Load command and the Initialize event
So something like
frmCriteria.Load
frmCriteria.Show
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Private Sub frmCriteria_Initialize()
frmCriteria.cboGroup.RowSource = "List!" & Worksheets("List").Range("A1:A" & Range("A" & Rows.Count).End(xlUp).Row).Address
frmCriteria.cboUnit.RowSource = "List!" & Worksheets("List").Range("B1:B" & Range("B" & Rows.Count).End(xlUp).Row).Address
End Sub
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Basically, you need to make sure you Load the data before you Show the form. If you hide the form instead of Unloading it, then the data would not automatically update just by re-showing the form. You would need to reload. Using Unload instead of Hide would take care of this, but always Loading before Showing is a good way to avoid any issues.
You may need to adjust the ranges I used. I was assuming the data you wanted to populate with started on Row 1, and that you wanted everything from those columns.
Let me know if you have any questions, or if it doesn't work properly.
Cheers,
WC