Detector rail doesn't work

The detector rail when used with a restone comparator delay will stop a minecart and then the power rails will turn on and make it go again shortly after but when hitting another detector rail with a delay on the same trip the minecart will stop but won't start again when power rail is set off. Hopefully I explained it well enoug . Love making rail systems in my cities! Hate to have to keep getting stuck every other detector rail stop.