I am struggling with PC's in a lab with exactly the same image. Some of them are added to the database successfully, others NOT. I use lslclient and supply the correct credentials for the relevant workgroups.
What is the exact error message you get?
Also, at our university we have many PC's within a single workgroup with different credentials. How do I specify these passwords.
This is not possible, you need a common credential, easiest way is to create a common user "lansweeper" on all machines.