Attempt to evaluate negative power of zero.

Hi all,

I'm trying to do corona discharge with the electrostatic and transport of dilute species modules, and currently got stuck with this probelm: Attempt to evaluate negative power of zero. - Function: ^ Failed to evaluate temporary symbolic derivative variable. - Variable: comp1.es.normE@VDN$z@VDN${conj@16} - Defined as: (((realdot(comp1.es.Er,comp1.es.Er)+realdot(comp1.es.Ez,comp1.es.Ez))^(-0.5))0.5)((-comp1.Vrz)+(-comp1.Vrz))

And also what does VDN mean?

Thanks so much!