Spell check not working when editing HTML

[Claus Atzenbeck]

Hi,

I use Vim 7.0 (on Mac OS 10.4.9). Spell checking works perfectly,
however, not when editing HTML files. Even after typing ":setlocal spell
spelllang=en_us", I don't get any error marks.

Other files, such as plain text or LaTeX, work perfectly with spell
checking.

Any idea why this could be the case?

Thanks,
Claus