Telerik RadGrid And Filtering _Replaced Null Values_ Issue

[SilverLight]

i have a BooundColumn in my telerik RadGrid like below :  

<telerik:GridBoundColumn DataField="Status" FilterControlAltText="Filter Status column"
    HeaderText="Status" SortExpression="Status" UniqueName="Status"
    FilterImageToolTip="Filter">
    <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" />
    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" />
</telerik:GridBoundColumn>

Status Column in my sql server 2008 database can accept null values and RadGrid shows them with an empty string.
so i replaced those Empty Strings with the codes below ?  

protected void grdSMS_ItemDataBound(object sender, GridItemEventArgs e)
{
    if (e.Item is GridDataItem)
    {
        GridDataItem item = (GridDataItem)e.Item;
        if (item["Status"].Text == " ")
        {
            item["Status"].ForeColor = Color.Red;
            item["Status"].Text = "Empty";
        }
    }
}

now my problem is i can not filter Empty Columns.  
how can i fix this issue? 

Note:
In the codes upper if (item["Status"].Text == " ") Correction Isif (item["Status"].Text == " ")

thanks in advance

[Princy]

Hi,

One suggestion is to replace the null values of the status field in the DataBase with a string to perform the filtering.

C#:

protected void grdSMS_ItemDataBound(object sender, GridItemEventArgs e)
{
    if (e.Item is GridDataItem)
    {
        GridDataItem item = (GridDataItem)e.Item;
        if (item["Status"].Text == " ")
        {
            item["Status"].ForeColor = Color.Red;
            item["Status"].Text = "Empty";
            // code to update the status field in the Database with string ("Empty").

        }
    }
}

Thanks,
Princy.