Function Macro Debug: Continue Onto The Do Loop At The Bottom That Does All The Work

I am having a problem with a custom funciton I am trying to create. It will exit after it is finished with the IF Then Else statement. I need it to continue onto the Do loop at the bottom that does all the work.

Function UPCECheck( num As String) As Long
Dim CheckNum As Long
Dim TempCheck As Long
Dim X As Long
Dim Holdtxt As Variant
UPCECheck = 0
CheckNum = 0
Debug.Print Len(num)
If Len(num) = 12 Then
Holdtxt = num
ElseIf Len(num) < 12 Then
Holdtxt = "000000000000" & num
Holdtxt = Val(Mid(Holdtxt, Len(holdtext) - 12, 12))
End If...................