problem in deleting from underlying table using gridview check boxes

Hi......I am able to delete from table using gridview whose checkboxes are not selected

Now what happening is, even my corresponding 
checkboxes are selected, simply all same company names get deleted even
if single company of similar name has unchecked check box


 
So i have mentioned in DataKeyName as Company 
  <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="4"
            DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="None" DataKeyNames="Company">
 
<asp:SqlDataSource ID="SqlDataSource1" runat="server" DeleteCommand="Delete FROM jobs WHERE [Company]=@Company" ConnectionString="<%$ ConnectionStrings:test_connectionstring %>"
&n ...