Checkpointing with a stepping stone analysis

[MartonaAlvarez]

I have been running mrbayes with the stepping stone option for comparison of tree topologies in a server and I reached the limit time in the server, so the analysis stoped. I want to restart the analysis from the checkpoint, added the append = yes to my nexus file, but I got this error:

Expecting NEXUS formatted file
   Reading trees block
      Successfully read tree 'mcmc.tree_1'
      Successfully read tree 'mcmc.tree_2'
      Successfully read tree 'mcmc.tree_3'
      Successfully read tree 'mcmc.tree_4'
      Successfully read tree 'mcmc.tree_5'
      Successfully read tree 'mcmc.tree_6'
      Successfully read tree 'mcmc.tree_7'
      Successfully read tree 'mcmc.tree_8'
   Exiting trees block
   Reading mrbayes block
      The parameter 'Tau' is fixed so the starting value cannot be set
      There was an error on at least one processor
      The error occurred when reading char. 11-11 on line 95
         in the file 'HG_75_tree_SC4.nex.ckp'

   Returning execution to calling file ...

      Error in command "Ss"
      There was an error on at least one processor
      The error occurred when reading char. 3-3 on line 53376
         in the file 'HG_75_tree_SC4.nex'

   Returning execution to command line ...

   Error in command "Execute"

I don't know how to fix it.

Thanks in advance

Marta