(?<=.+).+(?=</a>)
Most regex engines do not support regex pattern matching inside a lookbehind. According regular-expressions.infohttp://www.regular-expressions.info/lookaround.html, the only engines that do are provided by JGsoft, and the .NET framework.
I believe TextMate uses the Oniguruma regex engine.
See if this one meets your needs instead: (?<=>).*(?=</a>)