real random sampling on a small dataset

I'm trying to generate some random user agent strings by sampling a small exampleset with OS info, and another small exampleset with browser details. From each exampleset I want to take one random example, concatenate these and use it for some other processing later on.

I use the sample operator, absolute = 1 and this gives me indeed each time one single example from all of my sets. Unfortunatly it is each time exactly the same, so there seems no randomness involved. I assume this will only start as soon as you have a bigger set of examples but I would like to understand how to do this on a real small set also. Or how much example there are are needed to be able to get random results from the sample operator instead of each time the same one?

Attached some example showing the problem, the result is always the same even if it should be random in theory.