regexp [. .]

[applecom at inbox.ru]

I need to use regular expressions with a sequence of characters as a  
collating element.
 From re_format(7):
"Within a bracket expression, a collating element (a character, a multi-
character sequence that collates as if it were a single character, or a
collating-sequence name for either) enclosed in `[.' and `.]' stands for
the sequence of characters of that collating element.  The sequence is a
single element of the bracket expression's list.  A bracket expression
containing a multi-character collating element can thus match more than
one character, e.g. if the collating sequence includes a `ch' collating
element, then the RE `[[.ch.]]*c' matches the first five characters of
`chchcc'."
But grep (and other programs using regexp) writes on "echo somepattern |  
grep -Ee 'some[^[.pattern.]]'":
"Invalid collation character". What's wrong?