Who uses software nowadays ;|
Clearly, they're not correct type targa files. I had this when I tried some sky images, too. Try a few different editors that can save tga and see if any of them work, or see if you can save as type 2/10.
-is'nt it whateverlf.tga, and whateverrt.tga?
Correct. skylf, skyrt, skybk, skyft, skyup, skydn.