What kind of .tga files? Have you tried 24-bit instead of 32-bit?
Also, are you conforming to their Archive Structure?
http://modding.companyofheroes.com/asset-pack
-
#Steam AliasWL%Streak
- 1.44965.874+13
- 2.347180.658+2
- 3.697110.864+4
- 4.331126.724-1
- 5.379204.650+1
- 6.970420.698+1
- 7.854232.786+1
- 8.323143.693-1
- 9.467300.609+1
- 10.324117.735+1