HTTP Post from angular2 to .NET web api doesn't work

I'm building a site with an angular2 frontend and .NET backend, the GET calls to the backend have been working flawlessly.

Now I want to POST some stuff to my server, but I cant seem to get it working.

Angular 2 Service Method

postCategory(category: Category){
    let endpoint = this.url + 'add';
    let body = JSON.stringify(category);
    let options = new RequestOptions({headers: this.headers});
    return this.http.post(endpoint, body, options)
        .map((res:Response) => res.json())
        .catch((error:any) => Observable.throw(error.json().error || 'Server Error'));
}

Angular 2 DTO Model

export class Category{
    constructor(
        public CategoryName: string,
        public ParentId: number,
        public ChildCategories: Category[]
    ){}
}

.NET DTO Model

public class CategoryDTO
{
    public string CategoryName { get; set; }
    public int? ParentId { get; set; }
    public IList<CategoryDTO> ChildCategories { get; set; }

    public CategoryDTO(string name, int? parent, IList<CategoryDTO> child)
    {
        CategoryName = name;
        ParentId = parent;
        ChildCategories = child;
    }
}

.NET WEB API Controller

[HttpPost]
[Route("add")]
public IHttpActionResult PostCategory([FromBody]CategoryDTO category)
{
    var newCategory = _categoryService.AddCategory(_dtoBuilder.CategoryDtoToCategory(category));
    if(newCategory == null) return NotFound();
    return Ok(_dtoBuilder.CategoryToDto(newCategory));
}

The endpoints corresponds, the models correspond.

The call is being made, I put a break point on the start of my controller to see if it gets in but i doesn't. Am I missing something?

Thanks!

EDIT:

Method Get's calles here:

@Component({
    moduleId: module.id,
    selector: 'admin-category',
    templateUrl: 'admin-category.component.html',
    styleUrls: ['admin-category.component.css']
})
export class AdminCategoryComponent{
    name: string;
    parent: number;

    constructor(
        private categoryService: CategoryService
    ){}

    addCategory(): void{
        this.categoryService.postCategory(new Category(this.name, this.parent, null));
    }
}

Template of that component:

<h1>Add Category</h1>
<div class="form-group">
    <label for="name">Name:</label>
    <input type="text" class="form-control" id="name" [(ngModel)]="name">
</div>
<div class="form-group">
    <label for="parent">ParentId:</label>
    <input type="text" class="form-control" id="parent" [(ngModel)]="parent">
</div>
<button class="btn btn-default" (click)="addCategory()">Submit</button>