Re: VHDL compiling error with "not " operator : expression is not of type IEEE BALABA
Where are the libraries declaring the types vlbit and vlbit vector? why do these type even exist? In your posted code, you have not even included ieee.std_logic_1164.all, so you cannot even use std_ulogic.
The problem is because VHDL has strong typing, so a std_ulogic is not a bit, and a vlbit is not a std_ulogic. You have to do a type conversion to assign one to the other, and that often means writing a type conversion function. So Im guessing you havent written a custom not function that converts sin into a vlbit?
Basic answer - Dont use custom bit types. You should use standard libraries for everything.