Failure to merge trees after 1000 tries - Exponential Model

[Samantha Strickland]

I'm getting this error message when I try to run my xml file using

exponential model.

 

Fatal exception: failed to merge trees after 1000 tries!

java.lang.RuntimeException: failed to merge trees after 1000 tries!

 

I could perfectly run the same data set using constant and BSP model,

but not exponential. I've also tried different BEAST versions (1.5.4,

1.6.1 and 1.7.1) and got always the same message. I've also tried to use

UPGMA and a user-defined (newick format) as initial trees but then I got

zero probability error message (The initial model is invalid because

state has a zero probability). Is there anything else I can try? Why am

I getting this message only with exponential model?

 

Thank you!

Nazle