[pbmserv-dev] Zertz problem (I think)

[Lyman Hurd <LHurd@mediabin.com>]

In game 785 there is only one remaining space:            

     A4 B5 C6 D7 E6 F5 G4     ** Zèrtz (tournament) ** 
                              
              .               
           .     .            [marbles]    white   gray   black 
        .     .     .         
     .     .     .     .      reserve:       0       0      0 
        .  __ .     .         
     .    /  \   .     .      player1:       3       1      4 
        . \__/.  __ .         player2:       1       3      5 
     .  __/W \__/G \   .      
     __/W \__/B \__/.         
    /G \__/. \__/G \   .      
    \__/G \   . \__/.         next player: [player2] 
       \__/.     .            next action: add a marble, remove a tile 
              .               
                              
                       
     A1 B1 C1 D1 E1 F1 G1     

My understanding of the rules (and the server) is that the correct move is: 

bc4,xx 

The "xx" being server speak for cannot remove a tile since none are free
(that's what's on the help page). 

However, the server is responding: 

You can't remove this tile 

What am I missing? 

Thanks, 

Lyman