Shipping custom field

Hello, I have created extension for OC 2.0.2.0. I am now debuging some small issues and I have one problem. I used shipping_custom_field in order table in DB, it is serialized field and is working fine, until I try to edit order in admin. Everything is OK, except this field, which is overwritten as empty value ( a:0:{} ). I have stored my destination branch in this field and I cannot request shipping without this.

Thank you,

Michal

OK, I solved it... I used custom field wrong way. I realized, that I need to create custom field records in DB, or some edit functions do not rewrite it.