Function result using execute

I have a function which uses execute to populate the value of a variable
based on a defined select construct.

The relevant part of the code looks like thus:
EXECUTE curr_query INTO curr_amount;
RAISE NOTICE '%',curr_amount;
IF NOT FOUND THEN
curr_amount=0;
END IF;
RAISE NOTICE '%',curr_amount;

I've added the if found to trap if nothing is returned by the execute so
that the value gets set to a default 0 rather than null.

When I call the function, the first raise notice gives me a value that
is correct based on the select it would be performing, but the second
raise notice gives me a 0, which suggests to me that although the
execute has populated the curr_amount field with something, the IF NOT
FOUND is always firing.

Am I misunderstanding what the FOUND variable can be used for - i.e. is
it not compatible with/not set by the EXECUTE command and should
therefore I just be using a test of IF curr_amount IS NOT NULL?

Cheers,
Paul.

--
Paul Lambert
Database Administrator
AutoLedgers - A Reynolds & Reynolds Company