RuntimeBinderException: 'Cannot invoke a non-delegate type'

I'm trying to improve the performance of DynamicInvoke by

http://ift.tt/2B2cOwb

and Delegate.FastDynamicInvoke method of

http://ift.tt/1nCYYbq

Both EfficientInvoke and FastDynamicInvoke will throw RuntimeBinderException: 'Cannot invoke a non-delegate type' while DynamicInvoke work correctly.

What did I miss?