error in update in DataList in asp.net

hi
I have a datalist get picture from Databse
when i click on "Edit" the textbox and checkbox not get value(txtAlt_Txt , chk_Active)

<asp:UpdatePanel ID="UpdatePanel1" runat="server"><ContentTemplate><div align="center"><div style="width: 600px; margin-removed 80px;"><ul class="hoverbox"><asp:DataList ID="DataList1"
                            RepeatColumns="4"
                            RepeatDirection="Horizontal"
                            DataKeyField="ID_Pic"
                            OnEditCommand="DataList1_OnEditCommand"
                            OnCancelCommand="DataList1_OnCancelCommand"
                            OnUpdateCommand="DataList1_OnUpdateCommand"
                            OnDeleteCommand="DataList1_OnDeleteCommand"
                            runat="server"><ItemTemplate><asp:Label ID="lbl_ID_Pic" runat="server" Visible="False" Text='<%# Eval("ID_Pic") %>'></asp:Label><li><a href="#"><img src='<%# Eval("PinNameMD5") %>' alt='<%# Eval("Alt_Txt") %>' /><img src='<%# Eval("PinNameMD5") %>' alt='<%# Eval("Alt_Txt") %>' class="preview" /></a></li><asp:LinkButton
                                    ID="lnkEdit"
                                    CommandName="Edit"
                                    ValidationGroup="g"
                                    Text="Edit"
                                    runat="server" />
                                 |<asp:LinkButton
                                ID="lnkDelete"
                                CommandName="Delete"
                                Text="Delete"
                                ValidationGroup="g"
                                OnClientClick="return confirm('Are you sure?');"
                                runat="server" /></ItemTemplate><EditItemTemplate><asp:TextBox
                                    ID="txtAlt_Txt"
                                    Text='<%#Bind("Alt_Txt")%>'
                                     ValidationGroup="g"
                                    runat="server" /><br /><asp:CheckBox
                                    ID="chk_Active"
                                    Text="Active"
                                    Checked='<%#Bind("Active")%>'
                                     ValidationGroup="g"
                                    runat="server" /><br /><asp:LinkButton
                                    ID="lnkUpdate"
                                    CommandName="Update"
                                    ValidationGroup="g"
                                    Text="Update"
                                    runat="server" />
                                 |<asp:LinkButton
                                ID="lnkCancel"
                                CommandName="Cancel"
                                ValidationGroup="g"
                                Text="Cancel"
                                runat="server" /></EditItemTemplate></asp:DataList></ul></div></div></ContentTemplate></asp:UpdatePanel>

private void Galleryset()
    {
        DataTable dt=new DataTable();
        Dal.Fill_Dt("SELECT ID_Pic,'Wallpaper/thumb/'+ PinNameMD5 as 'PinNameMD5',Alt_Txt FROM Tbl_Glry", dt);
        DataList1.DataSource = dt;
        DataList1.DataBind();
    }
protected void DataList1_OnEditCommand(object source, DataListCommandEventArgs e)
    {
        DataList1.EditItemIndex = e.Item.ItemIndex;
       // DataList1.DataBind();
       // Galleryset();
    }
protected void DataList1_OnUpdateCommand(object source, DataListCommandEventArgs e)
    {
        Label lbl_ID_Pic = (Label)e.Item.FindControl("lbl_ID_Pic");
        TextBox txtAltText = (TextBox)e.Item.FindControl("txtAlt_Txt");
        CheckBox chk = (CheckBox)e.Item.FindControl("chk_Active");
        Dal.Cmd_Qry("UPDATE Tbl_Glry SET Alt_Txt=N'" + txtAltText.Text + "',Active='" + chk.Checked + "' WHERE ID_Pic='"+lbl_ID_Pic.Text+"'");
        Galleryset();
        DataList1.EditItemIndex = -1;
    }