Custom BB code {param} issue

[digatle]

I'm having difficulty getting a custom BB code working properly and I'm wondering if I have my syntax correct.

Tag: card

Works: <a href="http://magiccards.info/autocard.php?card={param}">{param}</a>
Doesn't Work: <a href="http://www.magiccards.info/autocard.php?card={param}" onclick="AutoCard('{param}'); return false;" title="{param}">

Example: [card]Wrath of God[/card]

What I need to have happen is when someone clicks on the card a popup window opens. The current method only takes them to the page.

Is there someone wrong with my code?

--------------- Added [DATE]1207603938[/DATE] at [TIME]1207603938[/TIME] ---------------

OK, I'm the idiot.

<a href="http://www.magiccards.info/autocard.php?card={param}" onclick="AutoCard('{param}'); return false;" title="{param}">{param}</a>