Robadope is indeed rather tricky to use and properly interpret the result.
The liquid is kind of salmon already and we have not found a way to change that yet.
Every now and then, I show this particular reaction with a Superman (pma/mdma pill) to visitors and I admit that they also have difficulties interpreting it.
Since I know what to look for, I agree that it is difficult to interpret a reaction (if it is there) but have a look at the picture again.
http://eztest.com/instructions.php
If there is a primary amine, there will be SOME sort of reaction. It may be hard to see but the little particles will turn reddish. A darker red than the color of the reagents. I have also seen that, once the reaction started, the liquid itself went slightly clearer. I don't know why but it is to explain that you may also see some unexpected 'reactions' every now and then, if it is a weird pill. The main thing is that reaction and the little particles in that reaction that get a color like in the picture.
http://eztest.com/instructions.php
Robadope is relatively new reagent. It INDICATES a primary amine. That means that if it is NOT there, there will be NO reaction. This is different from the other two reactions; if it is there, it will react.
It would have been better the other way around (if there is no primary amine, it should react) but that seems impossible with current chemical knowledge.
It also makes it rather difficult for us to properly communicate all pitfalls.
As other people also say, it seems to work.
We've verified our results with laboratory tests and it works.
It is just a different test from the other two and that requires a different approach. You are testing for something that should NOT be there.
Anyway, we've also seen stronger reactions with Robadope and if you really do not see any colorchange and reaction, your pill MOST LIKELY (no 100% guarantee!) does not contain a primary amine.
Just make sure you observe for at least 3-4 minutes.
Hope this helps
aj