Wh accumulator issue

Hi! I have a little problem with the Wh Accumulator function in the feeds on the emoncms.org site…

I have this feed configuration, the data are from an SD120C that i use from 2 years with good results.
From one week ago i reset all data and use only the instant consumption and the SDM120C internal couter for the daily consumption.

The problem is with “wh accumulator” function used to have the daily current usage from my external counter. If you see the image i make a x0.001 operation in order to have kWh from Wh counter and everything is good!
When i use the wh accumulator function for about some hours the system work greatly and i can see the 1-2 kWh of consumption but, without reason i can see the daily value with a big step ahead! I think is about the same amount of the kwh total read from SDM120C… is as if the “wh accumulator” function after some time adds the total count to the daily usage… why???