Strange warning: preg_match compilation warning

Does anyone have any idea as to why the following line is generating a warning? } else if (preg_match('/^([0-9]{4})-([0-9]{4})? (AVOIR \)$/', $content) === 0) { The warning text is as follows: Warning: preg_match(): Compilation failed: missing ) at offset 34 in ... Offset 34 seems to be the opening parenthesis of the preg_match function call...(??) Any help would be appreciated, googling simply brings up a load of busted websites... --Paul -- Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html