Hm- well the code works when I hard code it. So while I’d still go with a query, try:
<?php
$a = array( {exp:weblog:entries weblog="cpd_points" rdf="off" status="Approved" username="CURRENT_USER"}{cpd_points}, {/exp:weblog:entries} );
echo "sum(a) = " . array_sum($a) . "\n";
?>
It will have to be parsed on output for sure. If that doesn’t work- put just the weblog tag in a test template again- this time, look at the ‘reveal code’- make sure nothing else is getting in there- such as spaces, etc.
Don’t really have a good way to test this myself, so I’m winging it a bit.