Why can't I use Enumerable.OrderBy on this collection?

I was hoping to use OrderBy on a SPFolderCollection object but after I include System.Linq, OrderBy still does not come up in intellisense.

According to the Documentation, SPFolderCollectionClass inherits from SPBaseCollection which u开发者_开发知识库ses IEnumerable. I thought this was all that I needed, am I missing something?

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Most of the LINQ methods require an IEnumerable<T>, use the Enumerable.Cast method to convert it.

So x.Cast<SPFolder>().OrderBy(whatever).

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OrderBy will appear only on a IEnumerable<T> generic class. IEnumerable is different from IEnumerable<T>

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Perhaps you mixed up System.Collections.Generic.IEnumerable<T> interface and System.Linq.Enumerable class