  We extend the amplitude calculations of \cite{Lu:2009yx} to exhaust the
remaining cases for which one set of D$_p$ branes carrying a flux (electric or
magnetic) is placed parallel at separation to the other set carrying also a
flux but with the two fluxes sharing at most one common field-strength index.
We then find that the basic structure of amplitudes remains the same when the
two fluxes share at least one common index but it is more general when the two
fluxes share no common index. We discuss various properties of the amplitudes
such as the large separation limit, the onset of various instabilities and the
open string pair production. In particular, when one flux is electric and weak
and the other is magnetic and fixed, we find that the open string pair
production rate is greatly enhanced by the presence of this magnetic flux when
the two fluxes share no common field-strength index and this rate becomes
significant when the separation is on the order of string scale.
