why to create TO in LU04 for unblocking stock?

Hello Experts,

  I am new to WM area and trying to understand a concept.

I was trying to move stock from blocked status to unrestricted use.

As given in some threads it says we need to do PCN in MB1B and then create TO in LU04.

we need to create TO because we need to putaway the stock after it is unblocked?

I am not sure of the concept of using LU04.

Also when i did PCN it created negative stock in 922 area??

can please somebody explain?

Thanks,

Rakesh.