Constraint problem

When I instanse and use this class, time in simulator does’nt increases.
Why?
E1_NUM = 16
I want only 16 cells of time_slot_nodes have unique data in [0:15].
And only 16 cells of enable_nodes are 1.

class choose_time_slot;
        // rand bit[4:0] node_number[32*NUM_NODES];
		rand int time_slot_node[32*E1_NUM];
		rand bit enable_node[32*E1_NUM];
		constraint enable{
			foreach(enable_node[j])
				if(j % 32 == 0 || j % 32 == 31 )
					enable_node[j] == 0;
			enable_node.sum() == 16;
		}
		constraint time_slot{
			foreach(time_slot_node[j])
				if(enable_node[j] == 1)
					time_slot_node[j] inside {[0:15]};
			foreach(time_slot_node[i])
				foreach(time_slot_node[j])
					if( i != j)
						if(enable_node[i] == 1 && enable_node[j] == 1)
							time_slot_node [i] != time_slot_node[j];
		}
		
		constraint prirority{
				solve enable_node before time_slot_node;
		}

This constraint:

can never be satisfied. See Constraint with array reduction method