Executing Javascript on message load

Hi,

I’d like to track goals and events in my analytics software based on the conversation flow.

I tried adding this into the text response:

<script> _paq.push(['trackGoal', 2]); </script>

I can see it in the source code, but it doesn’t record a goal.
But when I add a button to the text response and click it, the goal gets recorded:

<button onclick="javascript:_paq.push(['trackGoal', 2]);">Test</button>

How can make the JS function execute on message load?

Thanks