I also tried Open Sans OpenSans-Regular, Open Sans Semibold.
What am I doing wrong?
Code:
calibre@server:~$ fc-list | grep "Open Sans"
/usr/share/fonts/truetype/open-sans/OpenSans-Light.ttf: Open Sans,Open Sans Light:style=Light,Regular
/usr/share/fonts/truetype/open-sans/OpenSans-CondLight.ttf: Open Sans,Open Sans Condensed Light:style=Condensed Light,Regular
/usr/share/fonts/truetype/open-sans/OpenSans-Regular.ttf: Open Sans:style=Regular
/usr/share/fonts/truetype/open-sans/OpenSans-ExtraBoldItalic.ttf: Open Sans,Open Sans Extrabold:style=Extrabold Italic,Italic
/usr/share/fonts/truetype/open-sans/OpenSans-Italic.ttf: Open Sans:style=Italic
/usr/share/fonts/truetype/open-sans/OpenSans-SemiboldItalic.ttf: Open Sans,Open Sans Semibold:style=Semibold Italic,Italic
/usr/share/fonts/truetype/open-sans/OpenSans-CondLightItalic.ttf: Open Sans,Open Sans Condensed Light:style=Condensed Light Italic,Italic
/usr/share/fonts/truetype/open-sans/OpenSans-ExtraBold.ttf: Open Sans,Open Sans Extrabold:style=Extrabold,Regular
/usr/share/fonts/truetype/open-sans/OpenSans-LightItalic.ttf: Open Sans,Open Sans Light:style=Light Italic,Italic
/usr/share/fonts/truetype/open-sans/OpenSans-Semibold.ttf: Open Sans,Open Sans Semibold:style=Semibold,Regular
/usr/share/fonts/truetype/open-sans/OpenSans-BoldItalic.ttf: Open Sans:style=Bold Italic
/usr/share/fonts/truetype/open-sans/OpenSans-Bold.ttf: Open Sans:style=Bold
/usr/share/fonts/truetype/open-sans/OpenSans-CondBold.ttf: Open Sans Condensed:style=Bold