I have a grid where you can select items, a drop down and a button. You can select an action from the dropdown and the click the button to open the modal dialog.
I need to put the id of the selected items in the Session first (IMPORTANT!), and then I need to open a Modal Dialog from code behind. I have tried a few solutions but the client code always get executed before the server code.

Thanks in advance,


UPDATE

This is the code in the aspx page

<telerik:RadComboBox ID="rcActions" runat="server" 
            DataTextField="Key" DataValueField="Value">
        </telerik:RadComboBox>
        <asp:Button ID="btnGo" runat="server" Text="GO" OnClick="btnGo_OnClick" />

    <telerik:RadGrid ID="radGrid1" runat="server" AutoGenerateColumns="false" AllowPaging="true" OnNeedDataSource="radGrid1_OnNeedDataSource"    OnItemCommand="radGrid1_ItemCommand" OnColumnCreated="radGrid1_OnColumnCreated"
        OnItemDataBound="radGrid1_OnItemDataBound">
        <MasterTableView AutoGenerateColumns="false" NoMasterRecordsText="<%$Resources:GlobalResource, noRecords%>">
            <Columns>
                <telerik:GridBoundColumn DataField="Id" UniqueName="Id" Visible="false">
                </telerik:GridBoundColumn>
                <telerik:GridBoundColumn DataField="UnitNumber" UniqueName="UnitNumber" Visible="false">
                </telerik:GridBoundColumn>
                <telerik:GridClientSelectColumn UniqueName="Selected">
                </telerik:GridClientSelectColumn>
            </Columns>
            <NestedViewSettings>
                <ParentTableRelation>
                    <telerik:GridRelationFields DetailKeyField="Id" MasterKeyField="Id" />
                </ParentTableRelation>
            </NestedViewSettings>
            <NestedViewTemplate>
                <asp:Panel runat="server" Visible="false" ID="InnerContainer">
                   <!-- Some code -->
                </asp:Panel>
            </NestedViewTemplate>
        </MasterTableView>
    </telerik:RadGrid>