After installing Umbraco 7.7.13 and trying to install Merchello FastTrack 2.6.0 there is an issue. After package install and when it tries to configure Merchello iguess.

 [NullReferenceException: Object reference not set to an instance of an object.]
   Merchello.FastTrack.Install.FastTrackDataInstaller.CreateSharedOptions() +69
   Merchello.FastTrack.Install.FastTrackDataInstaller.Execute() +141
   Merchello.FastTrack.Install.Installer.OnInit(EventArgs e) +105
   System.Web.UI.Control.InitRecursive(Control namingContainer) +392
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +204
   System.Web.UI.ControlCollection.Add(Control child) +157
   umbraco.presentation.developer.packages.Installer.ProcessInstall(String currentStep) +1147
   umbraco.presentation.developer.packages.Installer.Page_Load(Object sender, EventArgs e) +486
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +85
   System.Web.UI.Control.OnLoad(EventArgs e) +79
   umbraco.BasePages.BasePage.OnLoad(EventArgs e) +15
   System.Web.UI.Control.LoadRecursive() +130
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2837

First I have to install the nuget-packages, if not, the application breaks because the Merchello Core and FastTrack dll's are "missing".

Which version of Umbraco 7.7.x is recommended? Or can you fix above message somehow?