Sed replace error

Sed replace error

I have a pattern I am trying to match:
<x>anything</x>
I am trying to replace 'anything' (which can be any text, not the text
anything - (.*)) with 'something' so any occurrences would become:
<x>something</x>
I am trying to use the following sed command:
sed "s/<x>.*</x>/<x>something</x>/g" file
I am getting the following error:
sed: -e expression #1, char 19: unknown option to `s'
Can someone point me in the right direction?