How to fix regular expression error?

Question

Regular Expressions

Hello everyone, please tell me, I'm very stupid, what is the mistake?
I'm making a parser, everything works ok, only when I want to parse classes I can't get
a piece of code. When I delete class=\"(.+?)\" everything works, where is the error?
<tr id=\"(\d+)\" class=\"(.+?)\".+?<td.+?<a.+?<a.