Tested with matplotlib 1.4.3 and 1.5.3 built from sources - python 2.7.11 - Windows and Linux (64-bit)

To reproduce this issue, choose a set of values X so that -100<X<-10, then plot a NonUniformImage and attach a colorbar with a SymmetricalLogLocator : no tick or ticklabel will be displayed on the colorbar.