I got the following error when executing bulkcopy.

System.InvalidOperationException
The given value of type String from the data source cannot be converted to 
type decimal of the specified target column.

I use the following code.

DataTable empTable = DataTemplate.GetEmployees();
    DataRow row;
    for (int i = 0; i < gv.Rows.Count;i++ )
    {
        row = empTable.NewRow();
        string empName = gv.DataKeys[i].Values[0].ToString(); //first key
        string hourSalary = gv.DataKeys[i].Values[1].ToString(); //second key
        row["Emp_Name"] = empName;
        row["Hour_Salary"] = Convert.ToDecimal(hourSalary);
        row["Advance_amount"] = Convert.ToDecimal(0);
        row["Created_Date"] = Convert.ToDateTime(System.DateTime.Now.ToString());
        row["Created_By"] = Convert.ToInt64(1);
        row["Is_Deleted"] = Convert.ToInt64(0);
        empTable.Rows.Add(row);
    }
    InsertintoEmployees(empTable, "Employee");

My SQL datatypes for the above fields are:

Emp_Name nvarchar(50) ,
Hour_Salary numeric(18, 2), 
Advance_amount numeric(18, 2), 
Created_Date datetime,
Created_By numeric(18, 0), 
Is_Deleted numeric(18, 0) 

I don't know what I am doing wrong.