Oracle ORA-06502 numeric or value error on a procedure in c#

I created the following procedure:

create or replace procedure ps_medical (
   v_id in number,
   v_name out varchar2,
   v_description out varchar2
) is
begin
select name, description 
  into v_name, v_description 
  from medical_img 
  where id = v_id;
end;

It rises Oracle ORA-06502 numeric or value error. I want to display v_name and v_description.

My table structure:

ID            NOT NULL NUMBER                   
NAME          VARCHAR2(255)            
DESCRIPTION   VARCHAR2(255)

In Sql Developer it works fine. I'm trying to use it in a c# form and there the error rises:

try
{
    con.Open();
}
catch (OracleException ex)
{
    MessageBox.Show(ex.Message);
}

OracleCommand cmd = new OracleCommand("ps_medical", con);
cmd.CommandType = CommandType.StoredProcedure;

cmd.Parameters.Add("v_id", OracleDbType.Int32);
cmd.Parameters.Add("v_name", OracleDbType.Varchar2);
cmd.Parameters.Add("v_description", OracleDbType.Varchar2);

cmd.Parameters[0].Direction = ParameterDirection.Input;
cmd.Parameters[1].Direction = ParameterDirection.Output;
cmd.Parameters[2].Direction = ParameterDirection.Output;

cmd.Parameters[0].Value = Convert.ToInt32(tb_id.Text);

try
{
    cmd.ExecuteScalar();
    lb_med.Text = Convert.ToString(cmd.Parameters[1].Value);
    tb_desc.Text = Convert.ToString(cmd.Parameters[2].Value);
}
catch (OracleException ex)
{
    MessageBox.Show(ex.Message);
}
con.Close();