Degree Symbol missing in PolarPlot when exported to PDF

I am trying to produce a polar plot. The axis should be in degrees. While no error occurs, the pdf export isn't working properly. Instead of the degree symbol I get a square (while using acrobat) and a 'D' when I use nitro. The code I am using is

r = 2.81794*10^(-15);
m = 511;
a1 = 1/m;
a2 = 5.9/m;
ds1[theta_] :=
10*r^2*(1/(1 + a1*(1 - Cos[theta])))*((1 + Cos[theta]*Cos[theta])/
2)*(1 + (a1^2*(1 - Cos[theta])^2)/((1 +
Cos[theta]*Cos[theta])*(1 + a1*(1 - Cos[theta]))))
ds2[theta_] :=
10*r^2*(1/(1 + a2*(1 - Cos[theta])))*((1 + Cos[theta]*Cos[theta])/
2)*(1 + (a2^2*(1 - Cos[theta])^2)/((1 +
Cos[theta]*Cos[theta])*(1 + a2*(1 - Cos[theta]))))

Needs["PlotLegends"]
PolarPlot[{ds1[theta], ds2[theta]}, {theta, -π, π}, PolarAxes -> True,
PolarGridLines -> True, PolarTicks -> {"Degrees", Automatic},
PlotRange -> Automatic,
PlotLabel ->
Style[Framed["Klein-Nishina Compton Cross Section"], 20, Red,
Background -> Lighter[Yellow]],
PlotLegend -> {"1keV", "5.9keV"}, LegendShadow -> {.01, -.01}, LegendTextSpace -> 5,
LegendBackground -> LightPurple, LegendSize -> {0.5, 0.5},
Background -> LightYellow]

Export["Klein.pdf", %]


I also tried to export it in other formats, which is working fine, however I need .pdf format...

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Welcome to the site! Please try to post a Minimal working example that displays the behavior you want to show. – Dr. belisarius Sep 17 '12 at 16:21
Thank you for your warm welcome. You are propably true; that wasn't a minimum...I'll edit the question! – Thanos Sep 17 '12 at 16:23
@Thanos I get a degree symbol correctly when I export to PDF (Mac OSX 10.8, MMA 8.0.4). It could be because some fonts are missing on your system... – R. M. Sep 17 '12 at 16:24
@Thanos I also get a degree symbol when I export to PDF (Win 7 MMA 8.0.4). – David Slater Sep 17 '12 at 16:26
Try to add this option at the end of your PolarPlot: BaseStyle -> {FontFamily -> "Helvetica"} or any other font that is installed on your computer. – VLC Sep 17 '12 at 16:56

Force use of system fonts by the following:

SetOptions[EvaluationNotebook[],
PrivateFontOptions -> {"OperatorSubstitution" -> False}]


or

SetOptions[$FrontEnd, PrivateFontOptions -> {"OperatorSubstitution" -> False}]  Note: Options set for $FrontEnd are by default stored in the front end init.m file, and are persistent between front end sessions. (ref. \$FrontEnd)

Failing that try another PDF creator.

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I tried both ways but unfortunately it didn't work... I tried again with nitro reader and adobe acrobat reader nut the issue remains... I also tried with Ocular and Ubuntu's Document Viewer but again no degree symbol... – Thanos Sep 19 '12 at 8:53
What OS and version of Mathematica are you using? – Chris Degnen Sep 19 '12 at 9:01
I am running Mathematica 8.0.0 in Windows Vista. – Thanos Sep 19 '12 at 9:08
I also tried in FoxIt` but again nothing happened... – Thanos Sep 20 '12 at 6:38
How about CutePDF. Install, then File -> Print, select Printer Name: CutePDF Writer. Very reliable. cutepdf.com/products/cutepdf/writer.asp – Chris Degnen Sep 20 '12 at 8:16