I'm following the the Getting started article "Create Data Bound Chart" to bind a silverlight chart to a collection of my custom business object.
When the databinding happens I get an exception:
InvalidOperationException
No generic method 'Average' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic.
I already tried different collection types and value types in my business object which doesn't change anything. Any ideas on what I'm doing wrong?
Thanks for your help