Try
'Load Main CUI Name
Dim mainCuiFiles As String = Application.GetSystemVariable("MENUNAME")
mainCuiFiles += ".cui"
Dim cs As New CustomizationSection(mainCuiFiles)
'set default directory for your custom cui
Dim pwgscCui As String = DEFAULTDIR + "pwgsc.cui"
'Find out the current workspace settings name
Dim ws As String = Application.GetSystemVariable("WSCURRENT")
' check to see if partial cui is loaded
If cs.PartialCuiFiles.Contains(pwgscCui) = False Then
'if your cui isn't loaded it and refresh all workspaces
Application.MenuGroups.Load(pwgscCui)
'refresh current workspace to show toolbars and menu's
Application.SetSystemVariable("WSCURRENT", ws)
Else
'refresh current workspace to show toolbars and menu's
Application.SetSystemVariable("WSCURRENT", ws)
End If
Catch Ex As System.Exception
System.Windows.Forms.MessageBox.Show(Ex.ToString, "ERROR LOADING")
End Try

Loading Partial CUI's at Startup

Net

C#