Usually, a minecart on a detector rail generates redstone power. At the same time, powered rails transfer power from rails they are connected to. However, my uphill detector rails cannot power the powered rail uphill from them. Detector rails still work on flat surfaces and can transfer power downhill to powered rails, but cannot power powered rails adjacent uphill to them.

Have also attempted to replace powered rail with trapdoor; the trapdoor does not activate. Not sure if that info helps, Just thought to mention it.

(In all of the pictures bellow, the minecart is sitting on a detector rail)