custom regex

I just simply wanted to implement two rep tag **[example]** and **[solution]** I'm just turning these tags into h3 tags with a filter. I added those tags to the regex of the module. I changed the end of the line to this:
.... <h6|\*\*\[example\]|\*\*\[solution\]/i'
When I click edit link to edit/4 it opens the url edit/4 but with content from a different place of the page. Any idea?