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.

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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