Clock doesn't seem to tick
What you should do is make a bit of really simple test code to blink an LED at around 1 Hz.  If that works, then the clock is working.  This code can be incredibly simple:

module test(input wire clk, output led)

reg [31:0] cnt = 50000000;
reg led = 0;

always @(posedge clk) begin
    if (cnt &gt; 0) begin
        cnt &lt;= cnt - 1;
    end else begin
        cnt &lt;= 50000000;
        led &lt;= ~led;
    end
end

endmodule


If you can get that to blink and LED, then there must be some other issue with your code.  

Also, you should really make sure to specify the clock frequency in the UCF file to make sure that the tools will optimize your design correctly for the required clock frequency.