What other issues are there?

Images bigger than the phone's screen might cause problems. Try to resize the image appropriately before sending it to the phone. Also, images take up a lot of room on your phone -- you might be sending a 5k .jpg file, but it gets decompressed in the phone's memory and that could take quite a bit more memory. If you wish to get technical, it often takes (pixels wide) x (pixels high) x (color depth) bits or more.

If you want to upload a midlet, the .jar and .jad files must be identically named, except for the extension.

Specify the full, complete URL to the files in the .gcd and .jad files. Also, the colon has only one space after it. "Content-Type: image/jpeg" is good, "Content-Type:  image/jpeg" is bad.

Spaces in filenames is bad -- The SMS servers will not be able to handle them. Also, keep filenames short in size if possible. Long URLs also tend to cause problems.