I try to execute a Stored Procedure on Oracle 9I with an Output parameter and i get a cast error from Oracle.OracleString to String .... heres the code of the output parameter !

Dim myParam As Oracle.DataAccess.Client.OracleParameter = .Parameters.Add("@v_tan", Oracle.DataAccess.Client.OracleDbType.Varchar2, 12)
myParam.Direction = ParameterDirection.Output
m_objConnection.Open()
myCommand.ExecuteNonQuery()
Return Trim(myParam.Value)