  We present a dynamical lattice calculation with 2 flavours for bottomonium
states with an additional gluonic excitation. Using improved actions for the
quarks and gauge fields at a lattice spacing of $a \approx 0.1$ fm, we find
10.977(61)(62) GeV for the energy of the lowest lying $b\bar bg$-hybrid, where
the first error is statistical and the second denotes the systematic
uncertainty due to the determination of scale. In a parallel quenched
simulation we demonstrate explicitly that vacuum polarisation effects are less
than 10% of the splitting with the ground state.
