Delete row in gridview using linq

I wrote this code to remove rows from Gridview but it doesn't work.

code in class.cs:

public bool bDeleteItem(int nItemID)
{ 
    bool flag = false;
    try
    {
        Training_sNairoukhEntities1 sNairoukhEntities1 = new Training_sNairoukhEntities1();
        IMS_Items oIMS_Items = sNairoukhEntities1.IMS_Items.Where(Entity => Entity.ItemID == nItemID).Single();
        sNairoukhEntities1.IMS_Items.Remove(oIMS_Items);
        int nResult = sNairoukhEntities1.SaveChanges();
        if (nResult > 0)
        {
            flag = true;
        }
    }
    catch (Exception ex)
    {
    }
    return flag;
}

      

        
        
        
      

    

code in Aspx.cs:

int nId = Convert.ToInt32(gvManageItem.DataKeys[Convert.ToInt32(e.CommandArgument)]["ItemID"].ToString());
if (e.CommandName == "cmDelete")
{
    ManageItem oManageItem = new ManageItem();
    if (oManageItem.bDeleteItem(nId))
    {
        lblValidation.Text = "Delete is successfully";
    }
    else
    {
        lblValidation.Text = "isnt delete";
    }
}