frequency to voltage converter

Hey everyone,

I wrote a frequency to voltage converter and implementing it on a Altera Cyclone FPGA board( with an 64Mhz internal clock)

It works perfectly until it reaches 32 Mhz, at 32 Mhz it starts to countdown( decreasing instead of increasing)

Can someone please explain this weird thing?

module measure(

input wire signed [11:0] in,

input clk,

output wire signed [13:0] f

);

reg [15:0] in_count;

reg [15:0] out_count;

reg [15:0] clk_count;

reg clk_complete;

initial

begin

in_count=16'b0000000000000000;

out_count=16'b0000000000000000;

clk_count=16'b0000000000000000;

clk_complete=1'b0;

end

assign f[13:0]=({1'b0,out_count[15:5]});

always @(posedge clk)

begin

clk_count=clk_count+16'b0000000000000001;

clk_complete=1'b0;

if (clk_count==16'b1111111111111111)

begin

out_count<=in_count;

clk_count<=16'b0000000000000000;

clk_complete<=1'b1;

end

end

always@ (posedge clk_complete or posedge in[11])

begin

if (clk_complete==1'b1)

begin

in_count<=16'b0000000000000000;

end

else

begin

in_count<=in_count+16'b0000000000000001;

end

end

endmodule

Thanks in advance