not save json

[lyudad]

I set to session something like
{"name1":"lable1",
"name2":"lable2"}
then everything ok, but if i set
{"name1":"lable1",
"name2":"lable2",
"name3":[{"name11":"lable11", "name12":"lable12"},
{"name21":"lable21", "name21":"lable21"}
]}
this value not save in session