dropbear: no auth methods could be used

[shm]

I have created passwordless ssh connection between two nodes of an embedded 
target using dropbear. 
Dropbear is enabled "dropbear -s -g -E"

And I am able to login from one node(192.168.10.6) to the other 
node(192.168.10.5).
"dbclient -i /etc/dropbear/dropbear_rsa_host_key root at 192.168.10.5"

i'm trying to use OpenMPI  to run a program in two nodes . When i launch an 
MPI  program with mpirun from masternode(192.168.10.6), i retrieve the error:

"192.168.10.5: Connection exited, no auth methods could be used

A daemon (pid 1214) died unexpectedly with status 1 while attempting
to launch so we are aborting.

This may be because the daemon was unable to find all the needed
shared libraries on the remote node. You may set your LD_LIBRARY_PATH
to have the location of the shared libraries on the remote nodes and
this will automatically be forwarded to the remote nodes."

I have set LD_LIBRARY_PATH, but still doesn't work.
The problem occurs when running mpirun.
passwordless connection using dropbear was succesfull still Why is it showing 
"no auth methods could be used".?
Could you please help me? Thanks in advance