What was the criteria to activate the display channel?
From which version you upgraded?

From EPi 8 ... 8.4 maybe it was.

The trigger is not the problem....the channel doesn't even show upp in the preview list dropdown.

It looks some structuremap issue, its failing to register your channel to DisplayChannelService. double check the initialization.
/K

The initialization is running, I debugged it.

Could there be something new in web.config that is missing?

Took this from Alloy, it runs through init, but nothing appears in the UI...

[InitializableModule]
	[ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
	public class DisplayRegistryInitialization : IInitializableModule
	{
		public void Initialize(InitializationEngine context)
		{

			if (context.HostType == HostType.WebApplication)
			{
				// Register Display Options
				var options = ServiceLocator.Current.GetInstance<DisplayOptions>();
				options
					.Add("full", "/displayoptions/full", EPiServerApplication.ContentAreaTags.FullWidth, "", "epi-icon__layout--full")
					.Add("wide", "/displayoptions/wide", EPiServerApplication.ContentAreaTags.TwoThirdsWidth, "", "epi-icon__layout--two-thirds")
					.Add("narrow", "/displayoptions/narrow", EPiServerApplication.ContentAreaTags.OneThirdWidth, "", "epi-icon__layout--one-third");
			}
		}

		public void Preload(string[] parameters) { }

		public void Uninitialize(InitializationEngine context) { }
	}

Those I took from Alloy were the resolutions, forget about them :)

But also in Alloy, there is this Mobile channel, which not seems to be visible either...anyone knows how that channel works in Alloy?

I have installed  a new fresh Epi 9 site (Alloy), and there the DisplayChannel works just fine.

I have compared it with my site, and the only thing that differs is the initializations, which has all moved from global asax to separate initializationModules. 

The resolution (channels) are working now in my site, I took them from Alloy 9. But the DisplayChannel, refuses to initialize.

I have also changed from 4.5 to target the 4.5.2 .net.

Any thoughts are welcome...

Try browsing the following urls for any clues

/<episerverUI>/Shell/Debug/InitializationModules

/<episerverUI>/Shell/Debug/StructureMap

Ensure you are in the Administrators group and you have the following in your appSettings: 

<configuration>
  <appSettings>
    <add key="EPi.DebugView.Enabled" value="true" />
  </appSettings>
</configuration>

Ok added the appsetting

And tried:

mysite.se/episerver/cms/Shell/Debug/InitializationModules

 = 404

mysite.se/episerver/cms/Shell/Debug/StructureMap

 = 404

So… not working you mean? I am member of administrators

Tried to "reset views" under my settings?

try mysite.se/episerver/Shell/Debug/InitializationModules

Ok thanks Tahir

Both urls renders lots of stuff

Anything in particurlar I shall look for?

Tried that now Daniel but nothing happens, except that all view are reset

However, I tested to add a few lines manuelly in global asax and then it works...but this is not the right way to do it :-/

// Manual registration, should not be like this... but I had to do something
			var service = ServiceLocator.Current.GetInstance<DisplayChannelService>();

	        service.RegisterDisplayMode(new DefaultDisplayMode("WidgetPreview")
	        {
		        ContextCondition = (r) => !r.Request.Browser.IsMobileDevice
	        });

Yes that was the way to do it...in a initializationmodule

Wow, now after upgrading to 9.10.0, the preview channel is suddenly registered twice!

So...I removed my little manual register "fix" in global asax and then it is all back to normal again...weird isn't it!?

Epi has certainly been doing som experiments behind our backs here...

This was reported as a bug in EPiServer.CMS.Core 9.9.0 and fixed in 9.10.0.

http://world.episerver.com/documentation/Release-Notes/ReleaseNote/?releaseNoteId=CMS-3619