Usage report is different from provider

I monitor my usage every day as I have a 50 GB cap... Last month there was a 5 GB difference between Networx and the provider. This month, I am into my allotted parcel by 8 days and the difference is already 3 GB.
I am hooked directly to my computer with no router or wireless. Last month, I disconnected the line from my computer for 24 hrs and the provider says there was no traffic during that time. Networx also reported no traffic.
Am I doing something wrong or does Networx not report all traffic?

Is the Ignore LAN traffic option on? If so, it is common to expect up to 10% under-reporting because in this mode NetWorx does not record what's called TCP/IP overhead.

Even if this option is not enabled, up to 5% discrepancy is common. For instance some ISPs think 1 MB = 1000 KB, while NetWorx assumes 1 MB = 1024 KB precisely.

If you would like to equalise the readings, you can do so in the hidden settings. There is one parameter called Usage Adjustment Factor. Set it to a value that represents the difference (about 1.1) and NetWorx reading should match the ISP's ones more closely.

Thnx... I will try those settings...