Extracting and injecting A8R8G8B8 files?

[Synergy2069]

I was wondering if anyone has been able to extract and inject the A8R8G8B8 .dds format. I can extract a couple and inject them and everythings fine, then I try one more and an error pops up saying that it's not a valid halo2 map file. If anyone has any suggestions as to how to extract and inject or what may be causing the invalid file, please let me know. Thanks