How does a party get "officialy registered"? From the wikipedia article i see the Greek pirate party marked as "Active, unregistered" even though we could vote for them in the recent elections.
you can either become (I think) an observing member without the voting rights, or full member with voting rights.
What is wrong (in parent comments) is the meaning of being "registered". The map shows which parties are officially registered in their countries.
For example, PP-Sweden doesn't belong to PPI (oh, surprise!). Swedish representatives couldn't travel to Belgium because of eruptions of Eyjafjallajökull [1]
[1] http://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallaj%C...