Hi Andy, I think it may be because your code doesn't know which sheet it is supposed to run this on. Try declaring the sheet name, it should be similar to the following but perhaps with a different sheet name: 
Dim ws1 As Worksheet
    Set ws1 = Worksheets("Sheet1")
With the sheet declared, you can now specifically call the proper ranges like 
Do Until ws1.Range("F" & fircount).Value = cmdPassNum.Value And ws1.Range("H" & fircount).Value = ""
fircount = fircount + 1
Loop
You should do that for all ranges, rows, columns, cells, and whatever else requires explicit sheet calls. Let me know how it goes.