  We compute the "+" component of the electromagnetic current of a composite
spin-one two-fermion system for vanishing momentum transfer component
$q^+=q^0+q^3$. In particular, we extract the nonvanishing pair production
amplitude on the light-front. It is a consequence of the longitudinal zero
momentum mode, contributing to the light-front current in the Breit-frame. The
covariance of the current is violated, if such pair terms are not included in
its matrix elements. We illustrate our discussion with some numerical examples.
