You're super-cool!

Chain Round Robin.

Here is a current snapshot of one of the Round Robins I participate in (on the Postcrossing forum):

group 53 - MORE PEOPLE FROM THE SAME COUNTRY ALLOWED!
1. Solow | jess18877 -> 29.12.2010 | sheila -> 06.01.2011 | sent to synnin on 06.01.2011
2. Jess18877 | sheila -> 29.12.2010 | sent to synnin on 29.12.2010
3. Sheila | sent to synnin on 24.12.2010
4. Synnin | sent to wildernesscat on 05.01.2011
5. WildernessCat | jalutaja -> 03.01.2011 | solow -> 05.01.2011 | jess18877 -> 07.01.2011 | sheila -> 12.01.2011 | sent to synnin on 12.01.2011
6. Jalutaja | solow -> 06.01.2011 | jess18877 -> 10.01.2011 | sheila -> 18.01.2011 | sent to synnin on 18.01.2011

( A chain round-robin is a sort of a snail-mail game, where a participant takes a large postcard and sends it to the next person in his or her group. That person sends it to the next, the last sends to the first, and so on. This way the postcard gets filled with stamps and stickers, and eventually returns to the original sender, for keeps. What's the point? Get a lot of colorful stamps and cancellations from different countries, all on one card. )

As you can see, the cards in this group are progressing nicely, but for some reason they all get stuck in one place. Can you guess what the trouble is?