warning: array_keys() [function.array-keys]: The first argument should be an array in …modules\cck\modules\content_multigroup\content_multi‌​group.node_form.inc on line 315.

I created a content type which name is product. the product should have one or more features. each feature has two parts: one is feature title, the other is feature description. So what I need is a “feature” field with unlimited number of values.

After I upgrade from cck-6.x-2.9 to cck-6.x-3.0-alpha3, there is a module “content multigroup”. create a multigroup with unlimited value.

when I try to create a product page, there is an error “warning: array_keys() [function.array-keys]: The first argument should be an array in F:\wamp\www\drupals\sitepro\modules\cck\modules\content_multigroup\content_multi‌​group.node_form.inc on line 315.”

After I upgrade to cck-6.x-3.0-dev, the warning is fixed.