Trying to execute SASS from PHP via exec() function

I have a site with color setti开发者_如何转开发ngs in the admin. You change your colors, it saves a .scss file and runs exec('sass file.scss file.css'). Works fine locally (on MAMP), but fails on server. First, I turned off safe mode. Second, I checked, using exec(), to see if it had access to the anything. It did, but when running sass --help, sass -v, or anything with sass, no output was returned.

Anyone do this before or know what could be causing it? I'm running on Media Temple, if that helps.

a) Do you have sass installed on the target server?
b) Is the sass executable in your PATH?
c) See here for the meanings of exit codes
http://en.tldp.org/LDP/abs/html/exitcodes.html

126: Permission problem or command is not an executable