When working with an SQL Output parameters, you need to specify the parameter’s Direction property once you have created it. Here is a nice little example method:

private float checkValue()        {            SqlConnection con = new SqlConnection("Provider=PROVIDER;Server=SERVER;Database=DATABASE;");            SqlCommand com = new SqlCommand("getValue", con);            com.CommandType = CommandType.StoredProcedure;            SqlParameter par = new SqlParameter("@WB", SqlDbType.Float);            par.Direction = ParameterDirection.Output;            com.Parameters.Add(par);            con.Open();            com.ExecuteNonQuery();            float i = float.Parse(par.Value.ToString());            return i;        }Implementationfloat val = checkvalue();