Under what conditions does FinancialData return a ::notent message?

Question

I tried retrieving FinancialData for a few companies but when I tried doing it for NTDOY, I couldn't. As of 25/12/2012, querying

 FinancialData["PK:NTDOY"]

yields

FinancialData::notent: PK:NTDOY is not a known entity, class, or tag for FinancialData. Use FinancialData[] for a list of entities.

However, this is weird for two reasons. Firstly, PK:NTDOY is included in the list of financial instruments Mathematica supposedly has data for:

 FinancialData["*NTD*"]

yields

 {"JK:INTD", "NASDAQ:GKNTD", "NASDAQ:UNTD", "PK:ANTD", "PK:NTDMF", "PK:NTDOF", "PK:NTDOY"}

Secondly, if I try using free-form input, e.g.

= NTDOY price from 25 December 2011 to 25 December 2012

I get the same (notent) output; on the other hand, if I click on the orange "Show all results" plus symbol, I get a WA-like tab filled with meaningful data, even though sometimes Mathematica crashes while computing.

So my question is: what does FinancialData truly mean when it states that something is not "known"? Is this a software bug or is it simply that more data is available to WolframAlpha than is to Mathematica?

(I'm using Mathematica 8.0.1.0, by the way.)