Stop Error If Userform Cancel

I've got the following code as part of a userform

Private Sub cmbPlant_Exit(ByVal Cancel As MSForms.ReturnBoolean)
If cmbPlant.MatchFound = False Then
cmbPlant.BackColor = &HC0&
If MsgBox("Required!" & vbNewLine & "Please Select Correct Plant Number", vbOKOnly + vbExclamation, "Plant Number") = vbCancel Then Exit Sub
Cancel = True
Else
cmbPlant.BackColor = &H80000005
End If
End Sub

I also have a cancel button

Private Sub cmdCancel_Click()
If MsgBox(" Cancelling Will Clear This Form." & vbNewLine & " No Data Will Be Entered." & vbNewLine & "Are You Sure You Wish To Cancel?", vbYesNo + vbQuestion, "Cancel Data Entry") = vbNo Then Exit Sub
Unload Me
End Sub

If someone clicks the cancel button before using the plant # combo, the form closes, but the cmbplant_exit msgbox pops up too.