Not able to query loop with parameter - also crit error found

OK so this should be simple, but its not working. If I hardcode the value of id to 20 in the Loop the result works, but I can’t seem to pass refid into the loop and I can’t close the get tag without getting an error as I thought maybe that would be the problem. Also FYI – I tried passing id={URL query=referrer} into the loop and it caused a critical error on site…What am I missing here??

<Set referrer>20    </Set> 

<Set sharer><Url current />/?referrer=<Get name=referrer /></Set>

<a href="{Get name=sharer /}">SHARE ON FACEBOOK</a>
<Set refid><Url query=referrer /></Set>

<If check={Get name=refid}>
    <h3>Agent Spotlight</h3>
  <Loop type=user id={Get name=refid}>
    <If field=id value={Get name=refid}>
       <Field full_name /> <Field id />
      <User id />


I was able to resolve this. However thought you might like to know about critical error received…

The attribute needs to be quoted if it contains a space.

<If check="{Get name=refid}">

About the critical error, I’ll see if I can recreate it on my end.

Did it display an error message, or HTTP response status code?