  The authors of the Letter PRL 89, 017004 (2002) predict nontrivial flux
lattice structures in UPt3 in vicinity of the superconducting transition
between the A and B phases for low magnetic fields, an important conclusion for
motivating future experiments. We show that the approach and the conclusions of
this Letter are wrong. The transitions between the different superconducting
phases in the mixed state are pointed out to be rather crossovers than real
second-order phase transitions within the most popular theoretical models of a
two-component superconducting order parameter for UPt3.
