Error when passing arguments from ASP.NET to Oracle stored procedure.

Hello,

I am getting an oracle error when I run my oracle stored procedure from ASP.NET.  
But, I do not get this error when I run it from sqlplus and the results come out correctly.

The error message is: 'wrong number or types of arguments in call to 'test_procedure'
      ORA-06550: line 1, col 7
      PLS-00306: wrong number or types of args in call to 'test_procedure':

Background Info:
** I also know that the error is in the argument 'senditem'.  
** I tried to set it to 'varchar' in the oracle stored procedure - but the error still keeps coming
** Initially I got the 'no size set for string' for the 'senditem' argument and I fixed that by
specifying the size of the string when sending the parameters.

My 'test_procedure' in my oracle package is as follows:

PROCEDURE test_procedure(compnr IN long, pdno IN long, sitm IN string,  senditem OUT string ) IS
                tblname varchar2(30):='atable';
                qrystr varchar2(2000):='';
            
               BEGIN
                tblname:=tblname || to_char(compnr);
            
                qrystr := 'select t$sitm from ' || tblname ||
                       ' where t$pdno = :pdno_v and t$sitm =:sitm_v ' ;

                EXECUTE IMMEDIATE qrystr INTO senditem USING pdno, sitm;

I am passing the parameters when calling the above procedure from asp.net as follows:

      comp.Direction = ParameterDirection.Input;
      pdno.Direction = ParameterDirection.Input;
      sitm.Direction = ParameterDirection.Input;
      senditem.Direction = ParameterDirection.Output;

      oracmd.Parameters.Add(comp,OracleType.Int32,0);
      oracmd.Parameters.Add(pdno,OracleType.Int32,0);
      oracmd.Parameters.Add(sitm,OracleType.VarChar,24);
      oracmd.Parameters.Add(senditem,OracleType.VarChar,24);

Please let me know how I can resolve this issue. Thanks.