I seem to remember having an issue on my own server testing our a vbgallery install.
I dont remember off hand which one but it seems to me that under your php settings on the server you must allow these
Enable 'exec' function
Enable 'popen' function
Enable 'passthru' function
Enable 'proc_open' function
Enable 'shell_exec' function
Enable 'system' function
See if your host has any of those enabled and you can enable them as you need them to allow the install to run.