ERROR ack:679 - Unable to obey design constraints (LOC=DCM_X2Y1) which require the combination of the following symbols into a single component: Dcm symbol "inst_dcm_clk/dcm_clk" (Output Signal = NULL) Gclk symbol "inst_dcm_clk/clk0_bufg_inst" (Output Signal = clk0_obuf) The constraint fragments target to conflict component type.  lease correct the design constraints accordingly.