Paging Problem

Private Sub LoadData()
Dim keyword As String = Request.QueryString("kw")
Dim ds As New DataSet
ds = BusinessLayer.Usefull.FindBook(keyword.ToLower)

gv1.DataSource = ds.Tables(0)
gv1.DataBind()
End Sub
Protected Sub gv1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles gv1.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
gv2 = e.Row.FindControl("gv2")
gv2.DataSource = dtOutlines
gv2.DataBind()
End If
End Sub

Protected Sub gv2_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs)
CType(gv1.FindControl("gv2"), GridView).PageIndex = e.NewPageIndex
'Error Happens here, Object reference not set to an instance of an object
LoadData()
End Sub

HTML:
GV2:OnPageIndexChanging="gv2_PageIndexChanging"

Any Ideas??

Any Ideas??

Protected Sub gv2_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs)
ctype(sender,GridView).PageIndex=e.NewPageIndex
'Error Happens here, Object reference not set to an instance of an object
LoadData()
End Sub