That’s why a copy of the forum rules is Stickied (at the top) in every forum.
Can’t really help except to say I see the same issue. 8 bit tga works, 16/32 bit doesn’t. Don’t have many image apps to test in (certainly not PS) - old version of PSP (fails), a resonably recent Gimp (fails) and ImageMagik (fails).
Tested in Composite 32 and 64 bit (2012 and 2013).
Max 4.2 through 2014, Composite 2014.
nVidia 9800GTX+ (512MB) (Driver 314.22).
i5-3570K @ 4.4GHz, 8Gb Ram, DX9.0c.
Targa just can store 8bit per channel. It’s part of the specs. If you need higher bit depths per channel use EXR or DPX fileformat. Composite should give you a error message if you use bit depths not supported with the fileformat but it does not, never did.
Just make sure that your Rendersettings match the specs for the fileformat you’re using because composite does it not for you.