How to sort numerically, instead of by string, on a telerik RadGrid Asp.Net Ajax?

Question

I have a RadGrid that has a Loss Amount column which I would like to be able to sort. Currently it does sort, but only by string value. I have the column type as GridNumericColumn. Can someone point me in the right direction please? Thanks in advance.

Update:

Ok, here's my code. I am also formatting the column text to show the currency. One thing I did notice is that I am returning a string value from the Format method. Could this be the reason?

Column:

<rad:GridNumericColumn DataField="Loss Amount" UniqueName="Loss Amount" HeaderText="Loss Amount" SortExpression="Loss Amount" \>
<HeaderStyle Width="140">
<ItemStyle Width="140" HorizontalAlign="Right"ForeColor="Maroon" /> </rad:GridNumericColumn>

NeedDataSource Event:

protected void grdCustomerAssignments_NeedDataSource(object source, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
{
GetAssignments();
grdCustomerAssignments.DataSource = Assignments;
}

private void GetAssignments()
{
if (Assignments == null)
Assignments = new DataTable();

SPList list = SPContext.Current.Web.Lists["Listings"];
SPView view = GetCustomerView();
SPListItemCollection items = list.GetItems(view);

Assignments = items.GetDataTable();

foreach (DataColumn column in Assignments.Columns)
{
    column.ColumnName = XmlConvert.DecodeName(column.ColumnName);
}

Assignments.AcceptChanges();

}

ItemDataBound Event:

protected void grdCustomerAssignments_ItemDataBound(object sender, GridItemEventArgs e)
{
FormatCurrency(item["Loss Amount"].Text);
}

protected string FormatCurrency(string text)
{
if (text.Length > 3)
{
string result = String.Empty;
char[] tmpArray = text.ToCharArray();
Array.Reverse(tmpArray);
string tmpString = new String(tmpArray);

    while (tmpString.Length > 3)  
    {  
        string threeChars = tmpString.Substring(0, 3);  
        result = String.Concat(result, threeChars, ",");  
        tmpString = tmpString.Remove(0, 3);  
    }  

    result = String.Concat(result, tmpString);  
    tmpArray = result.ToCharArray();  
    Array.Reverse(tmpArray);  
    text = new String(tmpArray);  
}  

return String.Concat("$ ", text);  

}

Answer 1

Also check that the source field is of numeric data type and it is not string. You can test that easily enabling editing - if you edit an item an exception will be thrown if string value is attempted to be assigned to the Telerik numeric editor.

Dick