can test kits go bad?

[naatural]

Hia,

SWIM tried to test a pill the other day and there was no real colour change, maybe very slight darkening where the fragment was, but usually the whole solution drop would turn blue/black.

Then he realised the there was some kind of spill from one or more of the 4 solutions (EZ test xtreme) in the bigger container, and he noticed a kind of dark/grey dry residue covering some of the bottle and instructions leaflet.

He then decided to throw a tiny fragment of other mdma (which had before been tested) and it didn't really give a colour change either - same kind of slight darkening as the pill fragment

So maybe is it possible that the test kit solution has gone bad or something??? Does anyone know what could have made this happen/would it still do anything in the presence of mdma etc...

cheers!!