Using a Viper12 to run leds over 50-1000V range

Hi im struggling with a circuit im designing, im trying to run 3x 24V indicators using a Viper12 circuit. Ive set the circuit up as below:

The idea is that the pre circuit introduces the Zeners at 650V, offsetting the input to the Viper circuit by 400V however, when this happens the Zeners get incredibly hot but I cant see how. The Viper half is pretty standard to the application notes.

Could anyone help?

Thanks