Case layout does't update

Case layout does't update

Hi,
I created new cusstom fields for the Cases modul, then I modified the layout.
After that I created a web to case form.
Then i tried to modify the layout again, adding to the main section the standard "email" field, but it doesn't appear anywhere.

I red that a possibility was to change the profile language and then reset it again, so I tried, but nothig.

Can you urgently help me to insert the "email" standard field in the  case layout?

Thanks in advance.

Alessandro Masolo