Telerik.Web.UI, Version=2012.2.607.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4
3.) Replace "Assembly" on UserControl with strong name:
<%@ Register Assembly="Telerik.Web.UI, Version=2012.2.607.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4" ...
4.) Open Package.package -> Advanced -> Add -> Add existing assembly...
4.a) Source Path, e.g: C:\Program Files (x86)\Telerik\RadControls for ASP.NET AJAX Q2 2012\Bin35\Telerik.Web.UI.dll
4.b) Deployment Target: GlobalAssemblyCache
4.c) Location: Telerik.Web.UI.dll
4.d) Safe Controls: -> Click here to add new item...
4.e) Namespace: Telerik.Web.UI
4.f) TypeName: *
4.g) Assembly Name (e.g.): Telerik.Web.UI, Version=2012.2.607.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4
4.f) Safe: =Checked

<telerik:RadGrid ID="ProfileGrid" Width="100%" AllowFilteringByColumn="True" AllowSorting="True" PageSize="12" ShowFooter="True" AllowPaging="True" ViewStateMode="Enabled" runat="server" OnNeedDataSource="ProfileGrid_NeedDataSource" AutoGenerateColumns="false" GridLines="None" ShowStatusBar="true" AllowMultiRowSelection="True" DataKeyNames="ProfileID"> <GroupingSettings CaseSensitive="false" /> <MasterTableView> <Columns> <telerik:GridBoundColumn HeaderText="ProfileID" DataField="ProfileID" ReadOnly="True" UniqueName="ProfileID" Display="False" /> <telerik:GridClientSelectColumn UniqueName="CheckboxSelectColumn" /> <telerik:GridBoundColumn DataField="Email" HeaderText="Email" /> <telerik:GridBoundColumn DataField="FirstName" HeaderText="First Name" /> <telerik:GridBoundColumn DataField="LastName" HeaderText="Last Name" /> <telerik:GridBoundColumn DataField="Occupation" HeaderText="Occupation" /> <telerik:GridBoundColumn DataField="CompanyName" HeaderText="Company" /> <telerik:GridBoundColumn DataField="Source" HeaderText="Source" /> <telerik:GridBoundColumn DataField="ProfileLastModifiedDate" HeaderText="Modified" /> <telerik:GridButtonColumn Text="Delete" CommandName="Delete" /> <telerik:GridButtonColumn Text="View Full Profile" CommandName="View Full Profile" /> </Columns> </MasterTableView> <ClientSettings EnableRowHoverStyle="true"> <Selecting AllowRowSelect="True" /> </ClientSettings> </telerik:RadGrid>public partial class ProfilesGridControl : ProfileControlBase{ protected override void FillProfiles() { List<IProfile> profilesList = new List<IProfile>(); ProfileDal profileDal = new ProfileDal(); profilesList = profileDal.SelectAll(); ViewState["Profiles"] = profilesList; ProfileGrid.DataSource = ViewState["Profiles"]; } protected void ProfileGrid_NeedDataSource(object source, GridNeedDataSourceEventArgs e) { if (ViewState["Profiles"] != null) { ProfileGrid.DataSource = ViewState["Profiles"]; } { FillProfiles(); } }}