plotting - Exporting EPS figures with dashing from ListPlot

I am having difficulties exporting EPS figures. If I use the LineLegend option to create a dashed or a dot-dashed line, it seems ok in Mathematica 9.0 e.g.:

But the problem came out when the figure was expoted to EPS e.g.,

I use the following Mathematica code

G1 = ListPlot[{
      Table[{(i - 1) h, ρf[u, (i - 1) h, RKuOm, FB][[4, 4]]}, {i, 1, n - 1}],
      Table[{(i - 1) h, ρf[u, (i - 1) h, RKuOm, FB][[3, 3]]}, {i, 1, n - 1}], 
      Table[{(i - 1) h, ρf[u, (i - 1) h, RKuOm, FB][[2, 2]]}, {i, 1, n - 1}]
      }, 
      PlotRange -> All, MaxPlotPoints -> Infinity, Joined -> True, 
      PlotLegends -> Placed[LineLegend[{Directive[Purple, Thickness[0.14]], 
       Directive[Blue, Thickness[0.14], Dashed], Directive[Red, Thickness[0.14], 
       DotDashed]}, {Style["\!\(\*SubscriptBox[\(ρ\), \(44\)]\)", 22, Bold], 

       Style["\!\(\*SubscriptBox[\(ρ\), \(33\)]\)", 22, Bold], 
       Style["\!\(\*SubscriptBox[\(ρ\), \(22\)]\)", 22, Bold]}, 
      LegendMarkerSize -> {{35, 8}}], {{0.82, 0.4}}], AspectRatio -> 0.8, 
      PlotStyle -> {{Purple, Thickness[0.012]}, {Blue, Thickness[0.014], 
       Dashed}, {Red, Thickness[0.013], DotDashed}},  Frame -> True, 
      FrameStyle -> Directive[Thick, 15],
      FrameLabel -> {Style["\!\(\*SubscriptBox[\(ω\), \(1\)]\)t", 18], None}, 
      Epilog -> {Inset[Style["(a)", 24, FontFamily -> "Times", Bold], {6, 0.95}], 
               Inset[Style["G=0.1", 24, FontFamily -> "Times", Bold], {41.5, 0.61}]}]


Export["D:\\fermion.eps",G1,"EPS"];`

So, my question: why the style of the lines change? And how to solve?

Many thanks in advance.