edbproc window is empty

[wenhaihu]

when i test emacs23.3 + distel 4.0.3 on RHL5 followed the Bill's blog, http://bc.tech.coop/blog/070528.html, Open the source member (e.g. - "beersong1.erl") in Emacs
Start an Erlang Shell ("C-c C-z")
Connect Distel to the Erlang Shell ("C-c C-d n" + node name)
Compile the source member for debugging in the Erlang Shell ("c("beersong1", [debug_info]).")
Reload the Erlang module ("C-c C-d L") in the source buffer
Toggle debug interpreting of the module ("C-c C-d i")
Set a breakpoint at a line in the module ("C-x SPC")
From the Erlang Shell, run a function in the module ("beersong1:sing().")
The debugger's process list comes up in a browse window and I press RET on the process to select it for debugging (there can potentially be multiple processes that are being debugged at the same time)
The debugger window pops up
when i stop into "The debugger's process list comes up in a browse window and I press RET on the process to select it for debugging (there can potentially be multiple processes that are being debugged at the same time) ", and i press RET, i got one edbproc window, but the content is empty, anybody know why? and when i input command "n", the minbuffer show "peculiar error: [badarg [not-registered nil]]".
like this :http://www.digipedia.pl/usenet/thread/14327/360/