can't allow new tag in input format

hi!
Im have sam trouble with "Iput formats" - i can't allow the new tag in Filtered HTML.
Im add new tag in "allowed html tags" filds and click "Save configuration" button -
but after this the new tags (what I was added) not saved in the "allowed html tags".
There are default tags onliy in that field.
I was created new input formats, but this trouble is remain.
Any ideas?
thanks

[Heine - moved to support]