SQL 2008 Mirroring - failover looses owner

[rcamarda]

I have successfully configured mirroring in SQL 2008. I use a witness
server and it is running in sync mode. I can fail over the databases
and everything works great; except one thing.
I have a SQL user called dmbuilder. When I created the database via
SMSS I edit the properties of the database, choose files and change
the owner from my AD login to dmbuilder.
When the database fails over, I can not connect to the database. I
checked on the mirror (now primary) database, the owner is blank, so I
have to change it to dmbuilder and now I can use the database. When I
fail back, same thing, the owner is missing.
Someone suggested it has something to do with the endpoint
configuration of mirroring, but I can not find anything.
Any ideas?
TIA
Rob

[rcamarda]

I found a solution:
I needed to edit the properties of the user (dmbuilder) from the main
Security folder, then under User Mappings set the user as db_owner.
When I fail over the servers, the user assigned as dbo stays with the
database.
BTW, so far the testing of mirroring and failover is pretty stable.
Some of my applications wont use ODBC, so I going to have our security
guy configure an F5 load balancer to test for the status of the
servers.