Here's another way...
sbfrm = Choose(Nz(Me.cboPermitType, 0), "subfrmHotWork", "subfrmLineBreak", "subfrmConfinedSpace")
If IsNull(sbfrm) Then
MsgBox "Please select a Permit Type"
Else
DoCmd.OpenForm sbfrm, , , , acFormAdd
DoCmd.Close acForm, "frmPermitsearch", acSaveNo
End If