Config: 5.5 and Pervasive2000 Client/Server

We are using custom/pogrammed forms for our AddressBookHook. Whenever two user try to open the same record at the same time one of the user receives an error code 84 an the default/system form is opened. When the first user closes the (our!) record/form it still seems to be locked for the other users.

How can i unlock a record after i have opened/closed it with my forms?