Tried to connect redstone circuit to iron doors but doors would not open

Put the summary of the bug you're having here

What I expected to happen was...:
When i connect the door circuit to the rest of my redstone circuit and flipped the switch, the door would open.

What actually happened was...:
When i connected it and flipped the switch, nothing happened, no door opened. Even if i tried connecting a repeater to the block below the door block, it still wouldn't work. The door only would open, if a redstone torch was underneath.

Steps to Reproduce:
1. Create an XOR gate, with a switch on either side.
2. Create double iron doors
3. Add redstone circuit between iron doors and XOR Gate, so when the switch is triggered it should open both doors