"... Cannot Be Blank" - Even Though I Gived Good Values

scr.hu/6zp/aoey7 -> "create" -> scr.hu/6zp/9gdho . Product is default model and ProductController is default CRUD. What can be wrong?

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$model->attributes is ok.

Most probably category value is not assigned to an attribute because it’s marked ‘unsafe’ or is not present at method rules() array.

If that’s not the reason, please provide your code