In reply to cgales:
Loading work.muxtb
** Error: (vsim-3773) inter1.sv(28): Interface item ‘clk’ is not in modport ‘DUT’.
Region: /top/t2
** Error: (vsim-3043) inter1.sv(28): Unresolved reference to ‘clk’ in ob1.clk.
Region: /top/t2
** Error: (vsim-8440) inter1.sv(5): Clocking block input ob2.cb.a is not legal for the left hand side
of this or another expression.
Region: /top/t1
** Error: (vsim-8440) inter1.sv(6): Clocking block input ob2.cb.b is not legal for the left hand side
of this or another expression.
Region: /top/t1
** Error: (vsim-8440) inter1.sv(7): Clocking block input ob2.cb.sel is not legal for the left hand side
of this or another expression.
Region: /top/t1
these are the error lines shown while compiling @cgales