! pdfTeX error (font expansion): auto expansion is only possible with scalablefonts

I already installed cm-super and the error occurs when I try to compile the document with
usepackage{opensans}
instead of
usepackage{lmodern}
I updated all packages and checked the logfile to make sure cm-super is installed correctly:
s/MiKTeX/fonts/type1/public/cm-super/sfrm1000.pfb>