SginalTap: Some nodes not listed in NodeFinder?!

Ok, I understand, thanks for your explanation.

But somehow it still doesnt work, even with /* synthesis preserve */ (for my register).

I think it is something really weird: I reduced the whole design to only a few registers now, which are displayed in SignalTap after compilation. Let's say one of these signal is called read_base. Ok, but there is a register called r_res, which is not displayed. So what I tried now, is replacing each occurence of 'read_base' with 'r_res', simply changing the name, nothing else. And also, having the synthesis preserve attribute declared next to this register.

However if I now recompile the design and try to add the nodes, read_base disappeared now, okay. But there is no r_res listed in the node finder whatsoever.

How can this be?