Wierd SQL problem when calling StoredProc from Forms's JavaBean

Question

Hello,
I have a Oracle Forms form and it contains JavaBean that uses Oracle DB via JDBC. Wierd thing is that sometimes I get following error in Oracle Forms.
Error: ORA-06550 line, column 13: PLS-00201: identifier 'F1' must be declared ORA-06550: line 1, column 7: PL/SQL: Statement ignored.
What in earth this means? Sometimes I don't get it put after a while it starts appearing again.
F1 is a following function in DB:
CREATE OR REPLACE FUNCTION F1 ( PN$Param IN NUMBER )
RETURN VARCHAR2
IS
BEGIN
DBMS_LOCK.Sleep( PN$Param ) ;
RETURN ('Function ended at ' || To_Char(SYSDATE,'HH24:MI:SS') );
END;
My Oracle Forms Pushbutton code is following: (WHEN-BTN-PRESSED)
Declare
     LC$Res Varchar2(32000) ;
Begin     
Set_Custom_Property( 'EMP.BEAN',
1, 'INITCONN', 'jdbc:oracle:thin:@localhost:1521:demo') ;
Set_Custom_Property( 'EMP.BEAN', 1, 'INITUSER', 'scott' ) ;
Set_Custom_Property( 'EMP.BEAN', 1, 'INITPWD' , 'tiger' ) ;           
Set_Custom_Property( 'EMP.BEAN', 1, 'INITFUNC',
'begin ? := ' || 'F1(10);' || ' end;' ) ;
Message('Command sent'); synchronize;      
End ;
And JavaBean just fetch data using JDBC code below:
CallableStatement function = conn.prepareCall (sQuery);
function.registerOutParameter(1, Types.CHAR);
function.execute ();
sValue = function.getString (1) ;
function.close();
The purpose is to wait 10 seconds and then return time after that.
I have put JavaBeans code in jar file, signed it and declated it to Oracle Forms.
When I have created F1 I have granted execute public access:
grant execute on F1 to public;
Have anyone any ideas what could cause this kind of error?
Cheers!

Answer 1

Do they give support to their sample snippets?
Yep, StoredProc+PLSQL is taken from French site's sample to this sample
but that is the real issue of samples. Or do you disagree?
But I and my collague have same problems with same kind of thing.
One thing was that taking time from DB might charge more user rights... but I'm not sure. So, please tell if you know something. Quite mnny seems to have problems with that SP.