Help understanding switching voltage regulator (OKR-T/1.5-W12-C)
If I were you, this is what I would do first:


Read every page of the datasheet.
Is "pin 1" really what I think it is? The pin numbering on p. 12 of the datasheet runs in the opposite direction from what I expected.
Do I have every pin connected correctly, according to the input/output connection table on p. 12?
p. 14 recommends an input capacitor and mentions a "minimum external output capacitance required for proper operation", but neither is shown on the above schematic. Do I have at least the minimum recommended input and output capacitors?
Directly connect pin 1, the On/Off Control input, to GND or +Vin. The p. 3 of the datasheet mentions "a 49.2 KOhm pulldown to GND", and p. 4 mentions "The On/Off Control input should use either a switch or an open collector/open drain transistor references to -Input Common". The 10 MOhm on the above schematic is outside those guidelines. A 10 MOhm pulldown is weak enough to be easily overcome by exactly the sorts of high-current transient noise that I expect a switching voltage generator to produce.
Consider looking at each pin with an O'scope -- is it what I expected? (smooth, constant input and output voltages, without any significant transients or pulsing or ringing).


And if all that fails:


Ask for help, perhaps on Electronics Stackexchange.