Can't Open PDF - Code Included

With this code, I can open Word and Excel files, but not PDF. Please let me know what I'm doing wrong. (I tried changing strProg = "C:Acrobat.lnk" including to a .exe file but nothing happens when I click the Open button)

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Private Sub cmdOpen_Click()

Dim sSourcePath As String
Dim strProg As String
Dim objword As Object
Dim strFile As String
Dim XL As Object

sSourcePath = Me.FilePath

DoCmd.RunCommand acCmdSaveRecord

If fIsFileDIR(sSourcePath) = -1 Then

Select Case ParseFileName(sSourcePath, 3)

Case "xls"

Set XL = CreateObject("Excel.Application")

If IsNull(Me.FilePath) Then
MsgBox "You haven't Attached a File"

Else

With XL.Application
.Visible = True
.workbooks.Open Me.FilePath

End With

Set XL = Nothing

End If

Case "doc"

Set objword = CreateObject("Word.Application")

strFile = Me.FilePath

objword.Visible = True
objword.Documents.Open strFile

'--------------------------------------------------
Case "pdf"
'Open File

strProg = "C:Acrobat.lnk"

Call Shell(strProg & " " & sSourcePath, vbMaximizedFocus)


Case Else

MsgBox "File type not recognised"

End Select

Else

MsgBox "File cannot be found. Please check the file path. ", vbExclamation

End If

End Sub