Comparator redstone clocks not working with redstone mechanisms

So basicaly, when you build a comparator redstone clock, and conect it in a redstone mechanism (like an iron door or a piston), and turn on the comparator, the mechanism only activates once and does not activate again, like it should.

I tried it on diferent mechanisms to make sure this was certain, and indeed, it didnt work with none of all the redstone mechanisms.

Mojang, please fix this.