Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
A return code from the convert program of zero means success, anything else is an error. Make sure the return code is coming from the convert program. Try adding -debug all to see if any exceptions are thrown.
The debugging output tells us that the convert program is getting something other than the command line you sent it. Its getting an 'x' and '1200'. You'll need to determine why that is being passed to the convert program.
In ImageMagick 6.2.6-7 Beta we added a new log statement to display the actual command line being passed to the convert program to make debugging situations like yours easier. All you need to do is add -debug configure to the command line to get this information (and of course use ImageMagick 6.2.6-7 or above). The patch will be available by tommorrow.