enterprisedb package execution

hi to all this is rams i am using enterprisedb as back end here i found a problem

with package execution that is package stored procedures having output parameters r not executed through the vb dotnet application It does not recogize the output parameters

i submit my code and error below
Imports EnterpriseDB.EDBClient

Dim cn As New EDBConnection("server=192.168.10.129;user id=enterprisedb;password=spsoft;database=spruce;po rt=5444")
Dim cmd As New EDBCommand
cn.Open()
cmd.Connection = cn
query = "public.class_admin4.add_student(_sno,_sname,: p_class,_city)"
cmd.CommandText = query
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.Add(New EDBParameter("p_sno", EDBTypes.EDBDbType.Integer)).Value = 1
cmd.Parameters.Add(New EDBParameter("p_sname", EDBTypes.EDBDbType.Varchar)).Value = "rams"
cmd.Parameters.Add(New EDBParameter("p_class", EDBTypes.EDBDbType.Varchar)).Value = "xxx"
cmd.Parameters.Add(New EDBParameter("p_city", EDBTypes.EDBDbType.Varchar)).Value = "hyd"
cmd.Prepare()
cmd.ExecuteNonQuery()
MessageBox.Show("stored procedure is executed")
cn.Close()

error is

public.class_admin4.add_student(Integer) does not exists

regards

rams

kanchuparthi.rams