Priyanka,
Looking at your mxd, you are not solving the simple route problem but the travelling salesman option by checking on the "Reorder stops to find Optimal Route". With 454 locations, it will take a while to optimize the sequence. I suggest you let it run. It may take about 5 minutes to solve.
One thing you can do to make sure that their are no network connectivity issues is to turn of the Reorder option and then solve to make sure a route can be found between all the points.
Another thing I will point out is that your stop locations seem to be every house address along many blocks of streets. Do note that if you are trying to solve a chinese postman problem (e.g. postal delivery or garbage pickup) you will probably not get the most optimal result using the travelling salesman problem solver provided by the route solver.
Regards,
Jay Sandhu