Definition of "negative" magnetic field

Dear David,
Thanks for suggestion. It worked with you correction and:
B = 1.2D+00 and BTY = - ONEONE (to define a negative field)
When I put B = -1.2D+00 it did not work.
So I guess it was this issue.
Thanks again.

Dear Sophia,
indeed B cannot be negative, since it’s the magnetic field intensity. To orient the field in any desired direction, one has to properly define the direction cosines, as you eventually did.