Error - Unable to Lock Order

When getting this message, one of two things is the problem:

Someone has the Order open and needs to close it.
The user you opened the database with doesn't have read / write access to MSLLockDB. To confirm that the user has the approiate access to MSLLockDB, do the following:
1. Execute this query - INSERT INTO [MSLLockDB].dbo.[MACLOCKS] ([SessionID],[ServerName],[DBName],[TableName],[RowID]) VALUES(99999,'LockTest','test1','test2','test3')
2. If that query works the user has the appropriate access
3. Now delete the test record with this query: delete from [MSLLockDB].dbo.[MACLOCKS] where SessionID=99999