Newbie Question: gnc-price and Double Entry Accounting?

[Oliver Wahlen]

Hello all,
I want to use Double Entry Accounting for my Gnucash accounts.
One of these Accounts is a Stock Depot which is updated by gnc-price
daily.
Obviously gnc-price changes the value of this single Stock Depot Account
but does not reduce the amount of money on some other account.
Consequently the Double Entry Accounting mechanism does not work for me.

What is my mistake?

Oliver