I have a program with four tabs. How can activate the appropriate tab based on the file name of an image in an image control on a userform?

This is what I have but when I execute it and press the ok button, nothing happens. The program does not switch tabs, it just hangs.

Sub btnOK_click()
Call imagefill
End Sub

Sub imagefill()
    Select Case True
    Case preview.Picture = LoadPicture("C:/Documents and Settings/Mike/Desktop/Qwik Sheets/Portal Frame/frame1.bmp")
    Sheets("df1").Activate

    Case preview.Picture = LoadPicture("C:/Documents and Settings/Mike/Desktop/Qwik Sheets/Portal Frame/frame2.bmp")
    Sheets("df2").Activate

    Case preview.Picture = LoadPicture("C:/Documents and Settings/Mike/Desktop/Qwik Sheets/Portal Frame/frame3.bmp")
    Sheets("df3").Activate

    Case preview.Picture = LoadPicture("C:/Documents and Settings/Mike/Desktop/Qwik Sheets/Portal Frame/frame4.bmp")
    Sheets("df4").Activate

    End Select



End Sub