Expression Evaluate , error

  I have a questiion as to how this works , for example; 

= Expression.Evaluate( "a", 
[ a =  List.Sum, b =  List.Average ]  ) 
( {2,3,2,2} )

this will work fine, and jsut change to "a" or "b", to change result but  neither of these work ? 

= Expression.Evaluate( "a", 
[ a =  List.AnyTrue , b =  List.AllTrue  ]  ) 
( {2,3,4,true, 2,2} )  

or 

= Function.Invoke( 
    List.AllTrue   , 
    { {2,2,2,2,2}} )

 so why does it  not work and how can I get it to do so, i wanted to just be able to change a parameter to a or b and change 
the result . 

Richard.