can't parse link in a custom field

Hi

I’m using custom fields extensively in a website that I’m building and I can’t seem to get the following code to parse to the html
<a href="<?php $key="uni_weblink"; echo get_post_meta($post->ID, $key, true); ?>"

all my other keys are working fine except this one but they’re not within tags. is there something I’m doing wrong?

kind regards

Rebekah