Cant restart database because of orphaned lock ?

[Paul Taylor]

I'm using Derby in embedded  mode from my application, when I exit my 
application I close connection, and get connection with option 
:shutdown=true to shut it down
But sometimes when I restart my application it fails, so I try and 
recreate the database but  then receives exception with error code 45000 
(Database Already Running) , and I have to delete the database folder to 
get my application to restart

Am I doing something wrong ?
thanks Paul