Layers: Visio "makes it´s own changes"

[Katarina]

Hi!
I am drawing a map of systems and their connections. To be able to show only one type of service at a time I have tagged each system and connections with layers (named by functions)
My big problem is now that when I have tagged systems and connections with a function (layer) and then go back and filter for another function (layer), the Visio system has made changes on itself: Some systems and connections ("layer tags") are gone and some are added. I can't see why.
I have experienced this several times now so it can´t be me checking the wrong boxes or marking the wrong system.
And it seems impossible to go one, since any change in one layer will change in the other layers.

Please help me  to find a walk around. This drives me nuts.


More info that might be relevant:
The object data are linked to an excelfile
Object shapes include some of the object data
I am using Visio 2010

[Katarina]

I think I know what I did: The "assign layer function" is not addidive as it seems (I thought). So marking a bunch of objects and adding a layer will remove all earlier layer configurations for those objects.

I am so glad Ive found the problem!