[erlang-questions] Bad Argument, (Bug or something I'm missing).

[Chris Cook]

Morning list,

I have,

Erlang R15B01 (erts-5.9.1) [source] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.9.1  (abort with ^G)
1> List = "89234789234jhk2hk234892789fauky324978".
"89234789234jhk2hk234892789fauky324978"
2> <<List, <<"-">>/binary>>.
** exception error: bad argument

But when I write it as this,

3> <<"89234789234jhk2hk234892789fauky324978", <<"-">>/binary>>.
<<"89234789234jhk2hk234892789fauky324978-">>

I get the result I expected to get from the above 1 & 2. Could someone
please explain what is going wrong and why, because I'm very confused
with it.

Regards

Chris Cook.