The UBB needs to know the exact location of two programs installed on the server (these are installed by ImageMagick), they are morgify and convert.
Without knowing WHERE they are, it doesn't know what to do with files that need to be routed through them...
On my server they are /usr/bin/morgify and /usr/bin/convert but they can be installed in numerous locations; you'll need to ask your webhost and then populate the paths in the control panel.
