Graphics, Figures & Tables ⇒ Online entrys in bib with biber

[Alper98]

Hello guys,
right now im writing my bachelorthesis and have problems with my bibliography. Citavi declares some sources as online. Biber always give me the error

legacy year field ‚xxx‘ in entry ‚xxx‘ is not an integer- this will probably not sort properly.

The number is shown correctly in my pdf but I cant click on it and its not in the bibliography shown.

I hope someone can help.


Edit:
The problem was that some sourceentrys had more than one keyword and im sorting for keywords in my bib. Can i print one source twice?