problem with function in plpgsql

Hello;
I have a table pz like this :
Table = pz
+----------------------------------+----------------------------------+-------+

| Field | Type |
Length|
+----------------------------------+----------------------------------+-------+

| cle | int4 not null
| 4 |
| titre | varchar() not null
| 25 |
| typ | char() not null
| 1 |
| in_unit | int4 not null
| 4 |
| out_unit | int4 not null
| 4 |
| pcterr | float8
| 8 |
| a0 | float8
| 8 |
| af | float8
| 8 |
| desctype | varchar()
| 4 |
| description | int8
| 8 |
+----------------------------------+----------------------------------+-------+

I have to create a function who take me one row like that
create function test_exist_pz (text,int4,int4,float,float) returns text
as '
declare
pzrec pz%RowType;
begin
select * into pzrec
from pz
where typ = $1
and in_unit = $2
and out_unit = $3
and A0 = $4
and AF = $5;
if not found then
pzrec.cle = -1;
end if;
return pzrec;
end;
' language 'plpgsql';
CREATE
When I try to work with the function it doesn't I have this result :
seed=> select test_exist_pz('a',1,1,1.1,1.2);
ERROR: attribute 'pzrec' not found
I am not very familiar with plpgsql and so if there is somebody
who can help me or if thre is somebody who can say where can
I find documentation about plpgsql it is very well

Thanks

--
Basier Eric e-mail : basier(at)ipgp(dot)jussieu(dot)fr
http://geoscope.ipgp.jussieu.fr
IPGP Observatoires Sismologie-Volcanologie
4,Place Jussieu 75005 Paris Tour 24-14 4eme Etage Tel 01 44 27 38 96