I don't mean to be rude here, but the concept of going through Access to get from Excel to Powerpoint strikes me as a stupendously bad idea.

Also, I do a lot of office automation and I've never heard of this DDEInitiate thing you're using, so I suspect it's an older form of office automation, or maybe it's something you have to use in VBA (I do most of my stuff from VB, not VBA).

I'd suggest that you use a VB app to go from Excel to Powerpoint rather than embedded VBA in Excel. Include the Excel and Powerpoint object libraries in a VB project and then use the object browser to find the methods you want. I believe you can then use the methods in VBA if you really need to stay in Excel.