I am supposed to be using these modules to create a multiplier. I am getting an X for my product. Could you please spot my mistake?

$//$ Problem $1$

module partialMultiplier #$($parameter size$=4)($input clk$,$ reset, input $[$size$-1$:$0]$ A$,$ B$,$

output logic $[2*$size$-1$:$0]$ Product$)$;

logic $[2*$size$-1$:$0]$ ASum, PSum, sum$\_$out, shiftedA;

logic$[$size$-1$:$0]$ index;

logic B$\_$i$,$ Cout;

assign B$\_$i$=$B$[$index$]$;

Shiftreg #$($size$)$ shift$1($clk$,$ reset, A$,$ index$==0,$ shiftedA$)$;

Index #$($size$)$ index$1($clk$,$ reset, index$)$;

Mux$21$ #$($size$)$ mux$($shiftedA$,8\text{'}$d$0,$ B$\_$i$,$ PSum$)$;

RippleCarryAdder #$($size$)$ adder$1($ASum$,$ PSum, $1\text{'}$b$0,$ sum$\_$out, Cout$)$;

Accumulator #$($size$)$ accum$1($clk$,$ reset, sum$\_$out, ASum$)$;

assign Product $=$ ASum;

endmodule

module Shiftreg #$($parameter size$=4)($input clk$,$ reset, input $[$size$-1$:$0]$ A$,$ input Loadn,

output logic $[2*$size$-1$:$0]$ Y$\_$shift$)$;

localparam zero$=\{$size$\{1\text{'}$b$0\}\}$;

logic $[2*$size$-1$:$0]$ Y;

$//$ register

always$\_$ff @ $($posedge clk or posedge reset$)$

if $($reset$)$

Y size $\{1\text{'}$b$0\}\}$;

else

Y Y$\_$shift;

$//$ combinatorial, do shift

always$\_$comb begin

Y$\_$shift $=\{$size$\{1\text{'}$b$0\}\}$;

case $($Loadn$)$

$1\text{'}$b$0$ : Y$\_$shift $=\{$zero$,$A$\}$;

$1\text{'}$b$1$ : Y$\_$shift $=$ Y ;

default : Y$\_$shift $=\{2*$size$\{1\text{'}$b$0\}\}$;

endcase

end

endmodule

module Mux$21$ #$($parameter size $=4)($input $[2*$size$-1$:$0]$ A$,$ C$,$ input B$,$

output logic $[2*$size$-1$:$0]$ PSum$)$;

always$\_$comb begin

PSum $=\{$size$\{1\text{'}$b$0\}\}$;

case$($B$)$

$1\text{'}$b$0$ : PSum $=$ C;

$1\text{'}$b$1$ : PSum $=$ A;

default : PSum $=\{$size$\{1\text{'}$b$0\}\}$;

endcase

end

endmodule

module HalfAdder $($input A$,$ B$,$ output logic Sum, Cout$)$;

assign Sum $=$ A $^$ B;

assign Cout $=$ A & B;

endmodule

module FullAdder $($input A$,$ B$,$ Cin, output logic Sum, Cout$)$;

logic Sum$1,$ Cout$1,$ Cout$2$;

HalfAdder H$1($A$,$ B$,$ Sum$1,$ Cout$1)$;

HalfAdder H$2($Sum$1,$ Cin, Sum, Cout$2)$;

assign Cout $=$ Cout$1|$ Cout$2$;

endmodule

module RippleCarryAdder #$($parameter size$=4)($input $[2*$size$-1$:$0]$ A$,$ B$,$ input Cin,

output logic $[2*$size$-1$:$0]$ Sum, output logic Cout$)$;

genvar i;

logic $[$size:$0]$ Carry;

assign Carry$[0]=$ Cin;

generate

for $($i$=0$; i