A question about backgroundrb

I use backgroundrb to run task in background. But when I invoke a worker
defined in backgroundrb, I will get this error:

can't dump TCPSocket

vendor/plugins/backgroundrb/lib/backgroundrb/bdrb_connection.rb:72:in
`dump'
vendor/plugins/backgroundrb/lib/backgroundrb/bdrb_connection.rb:72:in
`dump_object'
vendor/plugins/backgroundrb/lib/backgroundrb/bdrb_connection.rb:86:in
`ask_work'
vendor/plugins/backgroundrb/lib/backgroundrb/rails_worker_proxy.rb:86:in
`send'
vendor/plugins/backgroundrb/lib/backgroundrb/rails_worker_proxy.rb:86:in
`invoke_on_connection'
vendor/plugins/backgroundrb/lib/backgroundrb/rails_worker_proxy.rb:72:in
`run_method'
vendor/plugins/backgroundrb/lib/backgroundrb/rails_worker_proxy.rb:25:in
`method_missing'

I am sure that the backgroundrb server is start. I use these code to
invoke this worker:

make_view_job_key=MiddleMan.worker(:worker=>:make_view_worker,:worker_key=>'mk_view_key')
make_view_worker=MiddleMan.worker(:make_view_worker,make_view_job_key)
make_view_worker.async_make_view

Can anyone help me on this?

Can anyone help me on this?