PDF printing-linestyle gaps

In SS3 using pdf.pltcfg, the gaps are disappearing on some linestyles. 

The line/gap patterns are defined as :  LS=2, 1.75, 1.05 mm, LS=3, 4.2, 2.4 mm, and LS=5, 1.4, 1.4 mm.  As shown below, the linestyles with smaller gaps print solid.  The print preview looks as expected, but the results are not.  Is there something about pdf.pltcfg that causes this?  Is the only solution to increase the gap sizes?