I was trying to insert formulas but when trying to insert operations, I found this following image. Can anyone tell me what's wrong and what can I do to fix it?

[Cookiste]

Help.PNG

[anon73440385]

Most probably you miss font Open Symbol opens___.ttf in Windows (Check %windir%/Fonts)

[mikekaganski]

… which is fixed in tdf#128226 for future 7.0.