This is generating the code fine. I get

<input type="radio" name="complete" value="1" />Yes
<input type="radio" name="complete" value="0" />No
<input type="radio" name="complete" value="-1" />N/A
[download]

which looks correct.

My guess is that the problem lies in the script that recieves the data. Do you by any chance have something like this in that script: if($q->param('complete')) because in that case it will return 0 and not enter the if. If this is that case try using if(defined $q->param('complete'))