Error: PLS-00306: wrong number or types of arguments in call to '' when executing pl/sql function from java

Hi!

I have the following problem. I am calling a pl/sql function from a JavaBean. The pl/sql function works perfectly, but when I call the bean, I get the error

Error executing statement: java.sql.SQLException: ORA-06550: line 1, column 13:
PLS-00306: wrong number or types of arguments in call to 'RETRIEVE_TECH_ID'
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

Here's the code that causes the error:
-------------------------------------------------------------------
qryStechsIDs = "begin ? := retrieve_tech_id(?, ?); end;";
cs = con.getConnection().prepareCall(qryStechsIDs);
cs.setString(1, rs.getString("RSLT_TABLE_NAME"));
cs.setInt(2, rs.getInt("RSLT_PK"));                  
cs.registerOutParameter(3, OracleTypes.CURSOR);
------------------------------------------------------------------

The pl/sql function gets 2 parameters: VARCHAR2 and NUMBER and returns a Cursor. I suppose that the problem is in the data type of the input parameters, but I just can't sort it out. So, how can I get rid of the stupid error?

Thanks for the help in advance!

BR,
al