Solved Serialize inventory of block

[Spartan9802]

Good morning. Hello,
I have a problem, I would like to serialize the inventory of a virtual chest that is contained in my variable here is my code

    open {backpack::%{_key}%} to {_p}
    set {_serial} to {backpack::%{_key}%}'s inventory's serialized contents
    send "%{_serial}%" to {_p}

 

[ChisleLP]

And the problem its?....

 

[Spartan9802]

It doesn't work, strangely enough this code if it works

set {_serial} to serialized contents of {backpack::%{_key}%}