Easy to blame the resin, but is the DI vessel assembled properly with you changing the resin? BTW, I'm not saying that the resin isn't good quality either. I'm just asking the question as it is a possibility that the fault is not just the resin.
On the subject of dodgy resin (we only supply Tulsion) here is a funny story.Outside our premises we had placed (but not yet disposed of) a very large commercial drum of DI resin which had been sent to us for evaluation a while ago. A few weeks ago some 'visitor' prised off the lid and helped themselves to half of its contents. They will have been disappointed when coming to use it as this is not standard resin but a grade of DI resin used in commercial applications and would be most ineffective when used to purify window cleaning water - it will probably have led to much annoyance Because we were about to dispose of the container we have not even bothered playing back the CCTV footage of the area to see who it was.