Word characters differ between spell files

Hi there! Recently I've started using vim, and tried to enable
spellchecking for russian.
So I've tried ":setlocal spell spelllang=ru". Vim said, that it doesn't
have spellfile for russian and
offer to download it, I accepted and allowed him to locate it in
~/.vim/spell/ru.utf-8.spl, also it downloaded ru.utf-8.sug.

Then, vim said:
"Error detected while processing /home/ridiculous/.vim/spell/ru.utf-8.spl:
E763: Word characters differ between spell files."

I'm not quite sure, what files does it mean, but I also have the same
spell files in /usr/share/vim/vim/73/spell directory. I've tried to
delete them, but it doesn't works.

Then, I've tried to open file on russian and enter command to enable
spellchecking. First, it gave me the same mistake, but for the second
time there was nothing on output, but still, there's no highlighting,
and "verbose set spelllang" gives me "spelllang=ru".

Here's my ~/.vimrc file, might be useful:

" To save, ctrl-s.
nmap <c-s> :w<CR>
imap <c-s> <Esc>:w<CR>a

" Поиск
set incsearch
set ignorecase
set smartcase

" Spell check
function! ToggleSpell()
if !exists("b:spell")
setlocal spell spelllang=en_us
let b:spell = 1
else
setlocal nospell
unlet b:spell
endif
endfunction
nmap <F4> :call ToggleSpell()<CR>
imap <F4> <Esc>:call ToggleSpell()<CR>a

" Folds
:nnoremap <space> za

" Shortcuts for moving between tabs.
" Alt-j to move to the tab to the leftnoremap <A-j> gT
" Alt-k to move to the tab to the right
noremap <A-k> gt

"XML
autocmd BufNewFile,BufRead *.xml source ~/.vim/ftplugin/xml.vim

" Google Translate
let g:goog_user_conf = {
\'langpair': 'en|ru',
\'v_key': 'T'
\}