Aircraft Textures not showing on some Aircraft

I've been having some trouble with some of the Aircraft I've downloaded. While their files transfer over to the correct placing. I find when I check to see if they're appearing in my Steam Flight Sim X; They're showing up as devoid of their textures, appearing stark white. I check the files and I see they're in there appearing as BMP files. But it's like my computer is unable to read them and so won't translate it to the game itself. It does this with some, in one instance the Luftwaffe Alphajet I had recently obtained and installed into Steam Flight Sim X. Is it a compatibility issue? If so, what steps would I need to take to get these texture files to work so the aircraft I've installed don't look like they were made from paper? 

Thank you in advance.