If none of the examples above to work there is a couple of things that needs to be checked. If not any of these quick fixes solves the problem then it is best to read the long version of the installation instructions before continuing the trouble shooting.
Verify that the GD library is really working by running
phpinfo() and check that your output includes a GD
section which should show similar information as the image below
Make sure you have enabled strict error checking and disabled output
php.ini. This might not solve the
problem by itself but it will enable (better) error messages to trouble
shoot the installation.
Make sure that you are using a recent version of PHP (e.g. ≥ PHP 5.2.x)
Make sure that the path to the TTF directories are correctly specified