Think is is propably caused by the backoffice caching.

Try to delete the cache and maybe restart the website.

Also i recommend to add the section with the new SectionService and also directly add the section to the current user with the UserService.

Sample:

var sectionService = ApplicationContext.Current.Services.SectionService;
//Try & find a section with the alias of "demoSection"
var demoSection = sectionService.GetSections().SingleOrDefault(x => x.Alias == "demoSection");
//If we can't find the section - doesn't exist
if (demoSection == null)
{
//So let's create the section
        sectionService.MakeNew("DemoSection", "demoSection", "icon-calendar-alt");
}
//Add the section to the allowed once for the admin
var us = ApplicationContext.Current.Services.UserService;
var admin = us.GetByProviderKey(0);
if(!admin.AllowedSections.Any(x => x == "demoSection")) {
admin.AddAllowedSection("demoSection");
        us.Save(admin);
}

I can confirm the code sample above is working fine by stepping through. It creates the section if needed and the admin user is allowed. Still nothing shows up on screen (in the users section area or the left hand sections toolbar). I did however notice when stepping through my tree and menu code is not being hit at all. I will attempt to resolve that next. Does the tree controller have to be placed in a particular directory where umbraco is expecting to find it? I assume that is the case. 

NOTE: to step through this code, I start debugging, no debug points will be hit in the application startup. If I make a change to the web.config, then refresh the umbraco page, the application will restart and your debug points will be hit. 

Tim - Markus's post is useful but a few bits and pieces have changed since he wrote it - take a look at Tim Geyssens blog post (works with Umbraco 7.1.4 - 7.1.6+) he's created a sample project here.

https://github.com/TimGeyssens/UmbracoAngularBackofficePages

Tim has two separate projects in his solution but I put my code inside the main Umbraco project with the backoffice angular stuff under a folder in App_plugins - ensure you use a package.manifest file for flexibility (basically Tim G's structure is good but I just create these extra folders in the main project). 

HTH. 

Using the original article, the project by Tim Geyssens and the following article I was able to build out this new section from scratch.

http://siempresolutions.co.uk/blog/ExtendingUmbracoCustomTreeandMVCAPIPart1

The only note is that there was something wrong with the original project I was working on. Since I was early enough along in development I just opened a test project, got the section working, then moved over all my code from the original project.

Glad my blog post was useful :) - I'd still recommend following Tim's for anyone else trying to do this. Dave Woestenborghs presented how to do this at the UK Umbraco Festival and had a nice, clean Umbraco content editor style section which would be a great starter point - look for the talks to be uploaded soon!

The reason why you probably had a problem in your original project (guessing a bit..) is that you created the section - spun Umbraco up and this automatically added it to the \config\trees.config and then, as you were still developing, you changed the name of the controller. 

This causes a bit of confusion as it won't recreate / update the section in the trees.config (as one with the same name seems to exist in the config) but also won't work as it can't find the controller. 

This would explain why it works in a new project - when you copied it over it spun up and created the correct config entry. 

HTH 

Steve

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