[jQuery] [Validation plugin] Checkbox array problem

[jQuery] [Validation plugin] Checkbox array problem


Hi,
I'm using Validation plugin (http://docs.jquery.com/Plugins/
Validation) and I want to use it to check whether at least one
checkbox is checked. Validating for one checkbox is working fine, but
not for group.
HTML code:
<input type="checkbox" name="category[]">
<input type="checkbox" name="category[]">
<input type="checkbox" name="category[]">
I tried to add "category[]: required" to rules but no success.
Could somebody show me a working example?
Thanks in advance,
nonsense