GraphConnection.List always return 100 results

Hi,

This is on a Programming C# question where whenever i make a graphConnection to find Group.

FilterGenerator groupFilter = new FilterGenerator();

groupFilter.Top = 25;

groupFilter.QueryFilter = ExpressionHelper.CreateStartsWithExpression(typeof(Group), GraphProperty.DisplayName, "GroupXXX");

graphConnection.List<Group>(null, groupFilter);

The results always return with 100 group?

Am i missing something?

Also, SOMETIME, this List<Group> will return Object Null Referecne Error (i mean really sometimes...) 

I'm using 

Microsoft.Azure.ActiveDirectory.GraphClient.2.0.3

Cheng