'Main Module
Option Compare Text

Public OEETag As String
Public OEEActiveControl As String

Public Sub OEE4Q()

Dim Ret As Boolean
Dim myForm1 As FilterOEE

Set myForm1 = New FilterOEE

Ret = IsWorkBookOpen("G:\Shared\MOS TBO\OEE\OEE- 4Q1.xlsm")

    If Ret = True Then
        SupervisorDept
        myForm1.Tag = OEETag
        Set myForm1.ActiveControl = OEEActiveControl '<--- Error occurs here
        GoTo SuperRepGen
    End If
    
    myForm1.Show

SuperRepGen:
    
    Select Case myForm1.Tag

'Rest of Code

End sub
---------------------------------------------------------
'sub which assigns tag and activecontrol.name based on username
Sub SupervisorDept()

    Debug.Print Username
    If Username = "aramaglia" Then
        OEETag = "ASY_FIQD"
        OEEActiveControl = "FIQD"
    End If
    
End Sub
---------------------------------------------------------
'Functions
Public Function Username()

    Username = Environ$("UserName")
    
End Function

Function IsWorkBookOpen(FileName As String)
    Dim ff As Long, ErrNo As Long

    On Error Resume Next
    ff = FreeFile()
    Open FileName For Input Lock Read As #ff
    Close ff
    ErrNo = Err
    On Error GoTo 0

    Select Case ErrNo
    Case 0:    IsWorkBookOpen = False
    Case 70:   IsWorkBookOpen = True
    Case Else: Error ErrNo
    End Select
End Function