Error(10327)cant determine definition of operator"="-found 0 possible definitions

LIBRARY IEEE; LIBRARY ALTERA_MF; USE IEEE.STD_LOGIC_1164.ALL; USE IEEE.STD_LOGIC_ARITH.ALL; USE IEEE.STD_LOGIC_UNSIGNED.ALL; USE ALTERA_MF.ALTERA_MF_COMPONENTS.ALL; ENTITY SCOMP IS PORT( CLOC...