Ahh. Another thing to try is exchanging the constant for its integer value.
wdPasteBitmap = 4 <-- this is word constant
ppPasteBitmap = 0 <-- This is a powerpoint constant
Using these constants when the code is running in other programs is often problematic. Try
Selection.PasteSpecial DataType:=4
This page tells you the possible datatype integer values
https://msdn.microsoft.com/en-us/lib.../ff197265.aspx