Lazarus IDE v2.2.0RC1 r65419 X64
FPC: 3.2.2
Think again, that does not make sence.
Note that you should focus on fpc. Lazarus has nothing to do with this.
TryAdd simply works, as demonstrated above.
If the example from Bytebites fails you have an old version and not a release version of 3.2.2..
BTW @Sarah: You have a sneaky way to implement features....Respect.