Script done... Function won´t work...

Once again, ;-)

The script is finally done i hope ...

i can create my function.... no problem
but when i'm calling it up with a
SELECT zufall(); statement pgAdmin
tells me there is no function with that name...
although its listed in my function list as zufall!!!! ...
<runningagainstthewallheadfirst>

SOURCE:
create or replace function zufall(int4) returns text as '
declare
anzahl alias for $1;
i int4;
zeichen char(1);
zufallstext text;
entries int8;
begin
loop
zufallstext := '''';
for i in 1..anzahl loop
select chr(trunc((random()*26)+65)) into zeichen;
zufallstext := zufallstext || zeichen;
end loop;
SELECT count(*) into entries FROM se_errorcode
WHERE entry = zufallstext;
EXIT WHEN entries = 0;
end loop;
return zufallstext;
end;
' language 'plpgsql';