Function created yet not found

Using PostgreSQL 7.1.3....

I start off without the function....

test=# select findparenttype(10056,'S');
ERROR:  Function 'findparenttype(int4, unknown)' does not exist
         Unable to identify a function that satisfies the given argument
types
         You may need to add explicit typecasts

So I create the function....

test=# create function findparenttype(int4, varchar) returns int4 as '
test'# select parent.entity_id from entity parent, entity child where
child.entity_id = $1 and child.lft between parent.lft and parent.rgt and
parent.type = $2;
test'# ' language 'sql';
CREATE

And then I try to use it:

test=# select findparenttype(10056,'S');
ERROR:  Function OID 14997123 does not exist
test=#

I've never seen that happen before, what causes something like this?  It
recognized that there was supposed to be a function with those
parameters, yet couldn't find it though I'd just created it.  Nothing in
the log indicates anything unusual to me.  I usually see this error when
the function I'm calling is referencing another function which has since
been dropped or reloaded, but you can see findparenttype doesn't
reference any other functions of mine.

I've been creating and dropping this function from the same script all
day without issues until now.

Thanks,
Fran