Why wasnt Barnbas kept in a coffin?

Totally confused here.  Hope someone can clear this up for me.

Willie opens the coffin.  Barnabas reached out and grabs his neck.
Later we find out that Barnabas has been in the coffin for hundreds or
years. Well sort of.

We go back to 1795 and he is put in with a cross across his chest but
no cross when Willie opens the coffin.  We go back to 1897 and he gets
out of the coffin so he shouldnt be there in 1966.  Back to 1840 and
for sure he shouldnt be there in 1966.

Can someone give us the correct way that things ran and tie this
coffin or not coffin thing together?