multi-source error!! -how to fix this error..?

module control_block( reset, enable, ext_clk, clk2, fast, slow, up, dn, DCO_CONTRL, phase_acquisition_mode, pll_lock );

	input reset, enable, ext_clk, clk2, fast, slow, up, dn;
	output [7:0] DCO_CONTRL;
	output phase_acquisition_mode, pll_lock;
	
	reg [7:0] DCO_CONTRL;
	reg pll_lock;
	reg mode_adjust_done;
	reg [5:0] pointer;
	reg phase_acquisition_mode;
	
	//mode adjust in the frequency acquisition mode
	always @( posedge reset or posedge ext_clk )
	begin
	 if( reset ) begin
		DCO_CONTRL[7] <= 1'b1;
		DCO_CONTRL[6] <= 1'b0;
		mode_adjust_done <= 1'b0;
		end
	else if( !clk2 ) begin
				if( !enable ) DCO_CONTRL <= DCO_CONTRL;
				else if( fast & !DCO_CONTRL[7] & !DCO_CONTRL[6] & !mode_adjust_done ) mode_adjust_done <= 1'b1;
				else if( fast & !mode_adjust_done ) begin
					DCO_CONTRL[7] <= 1'b0;
					DCO_CONTRL[6] <= DCO_CONTRL[7] & !DCO_CONTRL[6];
					end
				else if( slow & !mode_adjust_done ) begin
						mode_adjust_done <= 1'b1;
						DCO_CONTRL[7] <= ( !DCO_CONTRL[7] & DCO_CONTRL[6] ) | ( DCO_CONTRL[7] & !DCO_CONTRL[6] );
						DCO_CONTRL[6] <= !DCO_CONTRL[6];
						end
		 end
	end
	
	//adjust control register in the frequency acquisition mode
	always @( posedge reset or posedge ext_clk )
	begin
	 if( reset ) begin
		DCO_CONTRL[5:0] <= 6'h3f;
		pointer[5:0] <= 6'h20;
		phase_acquisition_mode <= 1'b0;
		pll_lock <= 1'b0;
	end
	else if( !clk2 ) begin
			if( !enable ) DCO_CONTRL <= DCO_CONTRL;
			else if( phase_acquisition_mode ) begin
					if( up ) begin
						pll_lock <= 1'b1;
						DCO_CONTRL <= DCO_CONTRL + 1;
					end
				 else if( dn ) begin
						pll_lock <= 1'b1;
						DCO_CONTRL <= DCO_CONTRL - 1;
						end
				end
				else if( pointer == 6'h00 ) phase_acquisition_mode <= 1'b1;
				else if( fast & mode_adjust_done ) begin
						DCO_CONTRL <= DCO_CONTRL - pointer;
						pointer <= pointer >> 1;
						end
				else if( slow & mode_adjust_done ) begin
						DCO_CONTRL <= DCO_CONTRL + pointer;
						pointer <= pointer >> 1;
						end
			end
	end
endmodule