When you create custom ribbon you need ribbon location
Much for my own reference, here is a list of default Ribbon location values in SharePoint 2010 Beta 2.
Remember to append .Controls._children to the end of each, and use CommandUI.Ribbon as the location for the CustomAction.
Ribbon.BDCAdmin.ActionManagement
Ribbon.BDCAdmin.ApplicationManagement
Ribbon.BDCAdmin.ApplicationModelManagement
Ribbon.BDCAdmin.PermissionManagement
Ribbon.BDCAdmin.ViewManagement
Ribbon.Calendar.Calendar.Actions
Ribbon.Calendar.Calendar.Aggregation
Ribbon.Calendar.Calendar.CustomViews
Ribbon.Calendar.Calendar.Expander
Ribbon.Calendar.Calendar.Scope
Ribbon.Calendar.Calendar.Selector
Ribbon.Calendar.Calendar.Settings
Ribbon.Calendar.Calendar.Share
Ribbon.Calendar.Events.Manage
Ribbon.Calendar.Events.New
Ribbon.Calendar.Events.Publishing
Ribbon.Calendar.Events.Share
Ribbon.Calendar.Events.Workflow
Ribbon.CustomCommands.Commands
Ribbon.DocLibListForm.Edit.Actions
Ribbon.DocLibListForm.Edit.Clipboard
Ribbon.DocLibListForm.Edit.Commit
Ribbon.Documents.Copies
Ribbon.Documents.EditCheckout
Ribbon.Documents.FormActions
Ribbon.Documents.Manage
Ribbon.Documents.New
Ribbon.Documents.Share
Ribbon.Documents.Workflow
Ribbon.EditingTools.CPEditTab.Clipboard
Ribbon.EditingTools.CPEditTab.EditAndCheckout
Ribbon.EditingTools.CPEditTab.Font
Ribbon.EditingTools.CPEditTab.Layout
Ribbon.EditingTools.CPEditTab.Markup
Ribbon.EditingTools.CPEditTab.Paragraph
Ribbon.EditingTools.CPEditTab.Styles
Ribbon.EditingTools.CPInsert.Links
Ribbon.EditingTools.CPInsert.Media
Ribbon.EditingTools.CPInsert.Tables
Ribbon.EditingTools.CPInsert.WebParts
Ribbon.Image.Image.Arrange
Ribbon.Image.Image.Edit
Ribbon.Image.Image.Properties
Ribbon.Image.Image.Size
Ribbon.Image.Image.Styles
Ribbon.Library.Actions
Ribbon.Library.CustomizeLibrary
Ribbon.Library.CustomViews
Ribbon.Library.Datasheet
Ribbon.Library.Settings
Ribbon.Library.Share
Ribbon.Library.ViewFormat
Ribbon.Link.Link.Behavior
Ribbon.Link.Link.Link
Ribbon.Link.Link.Properties
Ribbon.List.Actions
Ribbon.List.CustomizeList
Ribbon.List.CustomViews
Ribbon.List.Datasheet
Ribbon.List.GanttView
Ribbon.List.Settings
Ribbon.List.Share
Ribbon.List.ViewFormat
Ribbon.ListForm.Display.Actions
Ribbon.ListForm.Display.HealthActions
Ribbon.ListForm.Display.Manage
Ribbon.ListForm.Display.Solution
Ribbon.ListForm.Edit.Actions
Ribbon.ListForm.Edit.Clipboard
Ribbon.ListForm.Edit.Commit
Ribbon.ListItem.Actions
Ribbon.ListItem.Manage
Ribbon.ListItem.New
Ribbon.ListItem.Share
Ribbon.ListItem.Workflow
Ribbon.ManageTrust.Operations
Ribbon.Permission.Add
Ribbon.Permission.Check
Ribbon.Permission.Manage
Ribbon.Permission.Modify
Ribbon.Permission.Parent
Ribbon.PostListForm.Edit.Actions
Ribbon.PostListForm.Edit.Clipboard
Ribbon.PostListForm.Edit.Commit
Ribbon.PublishTab.Publishing
Ribbon.PublishTab.Workflow
Ribbon.SiteCollections.Contribute
Ribbon.SiteCollections.Manage
Ribbon.SiteCollections.Review
Ribbon.Solution.All
Ribbon.Solution.New
Ribbon.SvcApp.Create
Ribbon.SvcApp.Operations
Ribbon.SvcApp.Sharing
Ribbon.Table.Design.Style
Ribbon.Table.Design.StyleOptions
Ribbon.Table.Layout.Cells
Ribbon.Table.Layout.Properties
Ribbon.Table.Layout.RowsCols
Ribbon.Table.Layout.Summary
Ribbon.Table.Layout.Table
Ribbon.UsageReport.DateRange
Ribbon.UsageReport.Export
Ribbon.WebApp.Contribute
Ribbon.WebApp.Manage
Ribbon.WebApp.Policy
Ribbon.WebApp.Security
Ribbon.WebPartInsert.InsertRelatedDataToListForm
Ribbon.WebPartInsert.Media
Ribbon.WebPartInsert.Text
Ribbon.WebPartInsert.WebParts
Ribbon.WebPartOption.Arrange
Ribbon.WebPartOption.Commands
Ribbon.WebPartOption.InsertRelatedDataToListView
Ribbon.WebPartOption.Properties
Ribbon.WebPartPage.Actions
Ribbon.WebPartPage.Approval
Ribbon.WebPartPage.Edit
Ribbon.WebPartPage.Manage
Ribbon.WebPartPage.Share
Ribbon.WebPartPage.Workflow
Ribbon.WikiPageTab.EditAndCheckout
Ribbon.WikiPageTab.LibrarySettings
Ribbon.WikiPageTab.Manage
Ribbon.WikiPageTab.PageActions
Ribbon.WikiPageTab.Share