Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
ImageMagick determines the image type from its magic number (usually a few unique bytes in the first few thousand bytes of the image file), from its extention (e.g. image.gif), or from an explicit prefix (e.g. gif:/tmp/phpX16rjz). If it cannot determine the image type it throws an exception.
Check to ensure you can run the convert command from the command-line:
convert logo: logo.gif
If that works, make sure the permissions are set properly. Does the bulletin board software has read and execute permissions to the ImageMagick software.