please help me to clear this error

hi, i am working in c# asp.net.

my cs:

public void confirm(Object source,System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
if(e.Item.ItemType ==ListItemType.Item//e.Item.ItemType ==ListItemType.AlternatingItem)
{
LinkButton lb=(LinkButton)e.Item.Cells[0].FindControl("btndelete");
lb.Attributes["onclick"]="return(confirm('Confermi?'))";
}

}
i am using this coding to show confirm button while clicking the delete button.
this is my aspx:
<asp:datagrid id="DataGrid1" style="Z-INDEX: 101; LEFT: 160px; POSITION: absolute; TOP: 56px"
runat="server" OnDeleteCommand="cmddelete" DataKeyField="age" OnUpdateCommand="cmdupdate"
OnEditCommand="cmdedit" OnItemDataBound ="confirm" OnCancelCommand="cmdcancel" AutoGenerateColumns="False" OnItemCommand="insert"
ShowFooter="True" HeaderStyle-BackColor="#660033" HeaderStyle-ForeColor="white" BackColor="#660033"
ForeColor="#ffffff">

i did for edit,insert,delete allthe things correctly and works well, then i added this confirm delete, for this confirm i am getting the following error:

Compiler Error Message: CS0123: Method 'sqlserver.WebForm4.confirm(object, System.Web.UI.WebControls.DataGridCommandEventArgs)' does not match delegate 'void System.Web.UI.WebControls.DataGridItemEventHandler(object, System.Web.UI.WebControls.DataGridItemEventArgs)'

so please help me to solve this error,pleaseeeeeeeeeeeeeeeeTry Changing
public void confirm(Object source,System.Web.UI.WebControls.DataGridCommandEventArgs e)
To
public void confirm(Object source,System.Web.UI.WebControls.DataGridItemEventArgs e)
hi ferris, thanks for reply and i did modification as what u said, i am getting error in this,

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

public void confirm(Object source,System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemType ==ListItemType.Item||e.Item.ItemType ==ListItemType.AlternatingItem)
{
//LinkButton btn=((LinkButton)e.Item.FindControl("delete"));
//btn.Attributes.Add("onclick","return confirm('Are you sure you want to delete this company?');");
LinkButton lb=(LinkButton)e.Item.Cells[0].FindControl("btndelete");
lb.Attributes["onclick"]="return(confirm('Confermi?'))";
//b.Attributes.Add("onclick","return confirm('Are you sure you want to delete this company?');");
}
}

please help me to rectify this error.
Hi,

Try changing

LinkButton lb=(LinkButton)e.Item.Cells[0].FindControl("btndelete");
lb.Attributes["onclick"]="return(confirm('Confermi?'))";

To

LinkButton lb = (LinkButton)e.Item.FindControl("btnDelete");
lb.Attributes.Add("onclick", "return(confirm('Confermi?'));

hth