counter

I am currently using de1 board and Altera quartus II software. as a beginner to digital design, I am learning by going through the Altera lab exercise. I am stacked on trying to design a 4bit t ff based counter. my code counts up to7 without problem but it won't go further I was intending to count from 0 to 15 by instantiating my t ff 4 times as shown in the code below. Will you pleas help identifying my error?

module counter_4bit(q, En, Clk, Clr, );

input En, Clk, Clr;

output [0:4] q;

wire [0:2] temp;

tflipflop T0(q[0], En, Clk, Clr);

tflipflop T1 (q[1], q[0], Clk, Clr);

and(temp[0], q[1], q[0]);

tflipflop T2 (q[2], temp[0], Clk, Clr);

and(temp[1], q2, q1, q0);

tflipflop T3 (q[3], temp[1], Clk, Clr);

endmodule

module tflipflop(Q, t, Clk, Clr);

input t, Clk, Clr;

output reg Q;

initial Q = 0;

always @(posedge Clk)

if(Clr)

Q = 0;

else

Q = Q ^ t;

endmodule