Ghostscript无法在MAMP PRO中执行

I'm using MAMP PRO on my local machine and I have enabled the imagick extension in the PHP config file provided by MAMP PRO. I can see Imagick is listed under phpinfo(). I am attempting to create a thumbnail from an Illustrator file (.ai), but when I try this code...

$temp_file2 = '/path/to/vector.ai';
$image = new Imagick($temp_file2);

I get this error...

FailedToExecuteCommand `"/Applications/MAMP/Library/bin/gs" -q -dQUIET -dSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dAlignToPixels=0 -dGridFitTT=2 "-sDEVICE=pngalpha" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-r72x72"  "-sOutputFile=/var/tmp/magick-2814rSVJPY2macFe%d" "-f/var/tmp/magick-2814Z5tbjlN3yNHL" "-f/var/tmp/magick-2814fken20MxIbeq"' (-1) @ error/utility.c/SystemCommand/2051

So it can't execute the Ghostscript executable file? I thought MAMP PRO would just take care of this itself once I enabled Imagick?