Uhm, an interesting case.
The most likely reason why your transformerless power supply is only giving out 1.5V when you connect it to your load circuit is that the load circuit is drawing too much current. You can fix this by increasing the value of the resistor in series with the load.
So for troubleshooting your project, I would make sure that:
the load circuit is connected correctly,
the zener diode for damage is alright,
and also what about connections between the components.
I hope you'll be able to figure out the problem.