Clustering with ejabberd 2.1.5

Hi,

I wanted to enable clustering for my two servers using ejabberd-2.1.5.
I copied the erlang cookie from first to second and wanted to run the erl command (on second) described in the ejabberd guide:
erl -sname ejabberd     -mnesia dir '"/var/lib/ejabberd/"'     -mnesia extra_db_nodes "['ejabberd@first']" -s mnesia

I receive then the following crash log:

{error_logger,{{2011,9,21},{9,46,4}},"Protocol: ~p: register error: ~p~n",["inet_tcp",{{badmatch,{error,duplicate_name}},[{inet_tcp_dist,listen,1},{net_kernel,start_protos,4},{net_kernel,start_protos,3},{net_kernel,init_node,2},{net_kernel,init,1},{gen_server,init_it,6},{proc_lib,init_p_do_apply,3}]}]}
{error_logger,{{2011,9,21},{9,46,4}},crash_report,[[{initial_call,{net_kernel,init,['Argument__1']}},{pid,<0.20.0>},{registered_name,[]},{error_info,{exit,{error,badarg},[{gen_server,init_it,6},{proc_lib,init_p_do_apply,3}]}},{ancestors,[net_sup,kernel_sup,<0.9.0>]},{messages,[]},{links,[#Port<0.56>,<0.17.0>]},{dictionary,[{longnames,false}]},{trap_exit,true},{status,running},{heap_size,610},{stack_size,24},{reductions,467}],[]]}
{error_logger,{{2011,9,21},{9,46,4}},supervisor_report,[{supervisor,{local,net_sup}},{errorContext,start_error},{reason,{'EXIT',nodistribution}},{offender,[{pid,undefined},{name,net_kernel},{mfargs,{net_kernel,start_link,[[ejabberd,shortnames]]}},{restart_type,permanent},{shutdown,2000},{child_type,worker}]}]}
{error_logger,{{2011,9,21},{9,46,4}},supervisor_report,[{supervisor,{local,kernel_sup}},{errorContext,start_error},{reason,shutdown},{offender,[{pid,undefined},{name,net_sup},{mfargs,{erl_distribution,start_link,[]}},{restart_type,permanent},{shutdown,infinity},{child_type,supervisor}]}]}
{error_logger,{{2011,9,21},{9,46,4}},std_info,[{application,kernel},{exited,{shutdown,{kernel,start,[normal,[]]}}},{type,permanent}]}
{"Kernel pid terminated",application_controller,"{application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}}"}

Crash dump was written to: erl_crash.dump
Kernel pid terminated (application_controller) ({application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}})

Does anyone have an idea what goes wrong? Is it something that it can't connect to the first or what's the problem?

Thanks,
Michael