Lock sales order upon triggering of workflow

Hi Guys,

I have a requirement wherein I need to lock given sales orders upon the triggering of the workflow. This is to prevent other users from editing/modifying the same sales orders. I need to unlock the sales orders when the dialog task is sent to the intended users. I am trying ENQUEUE_EVVBAKE and DEQUEUE_EVVBAKE isndide my method but it does not work. Thank you guys for the help!