signals are ignored during functional simulation in Quartus Simulator

[Altera_Forum]

I got the below warning when running the functional simulation. I am not sure why bit 0 is ignored.. I tried to use preserve register & attribute preserve/keep but it doen’t help… 

 Warning: Ignored node in vector source file. Can't find corresponding node name "core_cpu:processing|stage_cpu:\state:1:st|out[0]" for functional simulation.     Any idea to solve the warning? Thanks..... 

[Altera_Forum]

Normally this happens, if the compiler minimzes the register for bit[0] as no output of the code depends on this bit.  

This does not mean necessarly that the bit is no longer in the code but the bit may no longer be accessible by it's intended name. The most easiest way is to add another vector to the code's outputs and assign the vector to the output, thus the bit cannot be optimized away, as it's now an output..

[Altera_Forum]

Thanks Carlhermann....Your answer is really helpful...