  In a recent letter, (Phys. Rev. Lett. 82, 2892(1999); cond-mat/9808306)
Kamien and Lubensky calculated the energy of the surface constructed via a
linear superposition of screw dislocations in SmA phase, and obtained the
positive (repulsive) sign of the long-range interaction between dislocations.
We would like to object that this interaction is attractive. This conclusion
can be important to explain the discontinuity of the TGB - SmA phase transition
in chiral liquid crystals.
