No data in performance graph showing 0 value

Hello,
I have a problem with the performance graph is not working. it's showing 0 value anytime. but I can get this graph in an old graph with mrtg. see the pictures attached. any idea to fix this issue.
Thank you
I have a problem with the performance graph is not working. it's showing 0 value anytime. but I can get this graph in an old graph with mrtg. see the pictures attached. any idea to fix this issue.
Thank you