Are you using delimiters with your regex and what regex function are you using to match?
heres one example:
$str = "\"string\",\"http://\"";
preg_match("%\"(.*)\",\"(ht{2}p://)\"%", $str, $matches);
echo $matches[1], $matches[2];
// outputs stringhttp://
I had to use 'ht{2}p' up there cause this stupid form kept automatically making it a link...arg