Open Adobe Acrobat by default over Reader VB6

I have Adobe Acrobat 5 and Acrobat Reader 5.1 on the same server. We need both because one application uses Reader and the other has to have Acrobat. In the VB6 application that calls Acrobat, the code is:
 
Set oAcrobat = CreateObject("AcroExch.App")
Set oDoc = CreateObject("AcroExch.AVDoc")
...remove menu items....
oAcrobat.Show
 
The problem is sometimes it defaults to open Reader even after I set the default in the registry to Acrobat. Is there a way to prgrammatically make sure I open Acrobat instead of Reader?