class="active" not created

Hi

I'm on 7.43 and are using Nice Menus 7.x-2.5. I just noticed a problem but can't say it is connected to Nice Menu, but I have to put the question somewhere.

When I under admin/structure/menus manually creates menu links, not all links produces class="active". After a while I found a pattern:

1. All nodes created by a Content type, like node/53, works just fine, there are class="active" in the menus
2. Just some of the Pages made manually under admin/structure/pages produces class="active"
3. Pages with a functioning class="active" has a link with a Path name like "anypage"
4. Pages not producing class="active" has a link with a Path name like "/anypage". The difference is the /.

So why do I not write the Path without / ? Because it is impossible for some Pages. On some I can write without / and class="active" will appear, but on others when I try to write without / I will have the message "The path 'anypage' is either invalid or you do not have access to it." When I add / in the beginning, I can creat the link but there will be no class="active"

As far I can see there is no difference at all in the settings between the different pages.

Can anyone give me a lead what this is all about. Please, I really want the active class in the menu.

Hans