I haven't tried PNG format of same image yet but i've tried compressed and uncompressed TGA. Compressed TGA images isn't supported by AGS. They're imported spoiled when compressed but still can be imported. So my problem is other than compression because i can't even import my TGA image. I have the error i mentioned Before importing. I can live with that but i wanted to share this problem with you in case you may have the same problem in the future.