php imap_search fails for subject strings which have apostrophe

I've to search for messages from Gmail Inbox over IMAP using search by SUBJECT . The php-imap imap_search() works fine when the subject is pure alphanumeric. If the subject string has an apostrophe or a dash then the search fails. imap_seach($mbox, 'ALL SUBJECT "<search string>"'); imap_seach($mbox, 'ALL SUBJECT "this is a string without quote"'); //Works imap_seach($mbox, 'ALL SUBJECT "this is a string with quote's and da-sh"'); //Doesn't Work I've tried using the Zend Framework IMAP library too, it fails too. I've been talking to people over some forums, they say subject search via imap on gmail works for them. What can be the problem here? I've tried escaping them but it did not help. Any help is appreciated. -- Regards, Nitesh Nandy