I don't know the answer to your specific question. However, I have noticed that there are issues on Cryptocoincharts as of late.

If you look at the historical data on NMC/USD you'll note that there's no information beyond the last month. If you select 3-month or 1-year, you still get the same 3 week span. Note that I'm using BTC-E as the source for data. It seems to work OK when selecting other exchanges, but not many trade NMC.  I've tried tweaking the link parameters, but that doesn't fix it. Maybe it is a BTC-E issue?

--Vinny