Unable to get Changesets in TFS Template 2013 -

i got problem trying develop custom activity tfs template in tfs 2013. first step changesets associated build. , after lot of tries , google have same problems : list empty. last attempt article : http://www.colinsalmcorner.com/post/tfs-2013-default-build--the-getenvironmentvariablet-activity

whatever tried, in custom activity i've nothing.

public sealed class changelogactivity : codeactivity<ilist<changeset>> {     [requiredargument]     public inargument<ilist<changeset>> associatedchangesets { get; set; }      protected override ilist<changeset> execute(codeactivitycontext context)     {         ilist<changeset> list = context.getvalue(this.associatedchangesets);         // list empty, not null     } } 

in template, it's got :

then variables,

then property of getenvironmentvariable task

and properties of activity

i don't know i'm missing. plus, don't know if it's related, trackbuildwarning nothing. thought context not one, how verify ?

i knew after posting question i'll find answer. simply, if between 2 successful builds no checkin made, associatedchangeset empty.

i can understand why, build display tricky. says @ top "build started blabla associated changeset 14"

so supposed wrongly can information...