dresali: well, it wouldn't allow you to make that first capture either: remember: you can't jump a piece twice, meaning that when you jump to g9, you can't backtrack and jump d6 as well.
So the possibilities are:
27. b10xe7xg9 or 27. b10xe7xb4 or 27. b10xe7xc5

If either one of the above doesn't work, then do send a bug report to Fencer, but I think his implementation is probably sound as it is...;)

Hi,
maybe some checkers adept can enlighten me here:

In this game International Checkers (dresali vs. crayzeejim)
shouldnt I be able to move
26. ... b10xe7xg9xb4 and
26. ... b10xe7xg9xc5 ?
It doesnt allow me to make the last capture, and I wonder why.

Thanks for any advice.

as you all know and have been looking forward to with such anticipation: The Dutch Championship has just kicked off!
And what's more: the games can be followed live: http://www.livedraughts.com/NK2008/LiveGames1x4_1x3.htm
a service provided by http://www.livedraughts.com/
A good site to bookmark, since quite a few major tournaments and events will be provided by them (e.g. the upcoming worldrecord attempt for blind simultaneous games by Erno Prosman)

More specifically related to the present championship: for reviews of past rounds see: http://www.dcdordrecht.nl./ and click on "Animatie en analyse" then "Kampioenschap van Nederland" and on 1-13 to go to the desired round... (of course comments there will be in Dutch, but the notation is universal :)

Tiny note: the electronic boards do sometimes have difficulty "seeing" the pieces on the board, a bug which may confuse but is usually resolved one move later. Enjoy!