  The vacuum expectation value of the electromagnetic energy-momentum tensor
between two parallel plates in spacetime dimensions D > 4 is calculated in the
axial gauge. While the pressure between the plates agrees with the global
Casimir force, the energy density is divergent at the plates and not compatible
with the total energy which follows from the force. However, subtracting the
divergent self-energies of the plates, the resulting energy is finite and
consistent with the force. In analogy with the corresponding scalar case for
spacetime dimensions D > 2, the divergent self-energy of a single plate can be
related to the lack of conformal invariance of the electromagnetic Lagrangian
for dimensions D > 4.
