Change the line
ImgPath = ThisDocument.Path
to
ImgPath = ThisDocument.Path & "\"
better still
Sub Logocheck()
Dim ImgName As String
Dim ImgPath As String
    ImgPath = ThisDocument.Path
    ImgName = Dir$(ImgPath & "\*logo*")
    While ImgName <> ""
        MsgBox ImgName
        ImgName = Dir$()
    Wend
End Sub