Clock issues with Alesis HD24

[gpgarner]

Here's the deal: I use an Alesis HD24 to track to, then I dump via lightpipe into Pro Tools, edit, then dump back to the HD24 to mix. Going into PT is fine, however, when trying to dump back to the HD24, there is a clock issue that causes pops. I have tried the following. 1. Set Pro tools clock to internal, HD24 clock source to Optical. 2. Pro Tools clock to ADAT, HD24 to internal. 3. Every concievable transport option even though I know its a clock issue. Am I going to have to get an external clock generator for these to pieces of gear to lock? Any insight or suggestions would be appreciated. thanks