start by trying another fish plecos are dang near inposable to breed thats why they cost so much. mater a fact last time i check it hasnt been done.i do know how they do to give you start to try. the breed in side holes they make in the mud on the side of river banks thats about all the info i could find.
they are not impossibe and many many of them have been bred right here in the us. most breed in caves which you can buy for about 5$ or so off the internet here is one place plecocaves.com