@uveso Thanks for your fast answer...
But its still exactly the same Problem...
Everything works fine UNTIL i edit the .dds in Photoshop...i can use every .dds from Gamedata, but after editing its yellow in Game.
After im finished with editing i go for "save as.." -> ".dds" and then a NVIDIA Setting window pops up....Do i have to change there some settings? e.g. the Format? im on RGBA 8 bpp / explicit alpha as you see in the following picture: