awstats vs ispcp traffic log!

[bulforce]

First i know that there is another thread on the board regarding this, however i am starting new one because with me the problem is different. Unlike the problem described in the other thread i am experiencing the opposite effect. My awstats logs are showing more traffic than the ispcp.

Example:
For yesterday(Dec 2nd)

Awstats is reporting: 1.41 GB traffic usage(Probably counting only web traffic)
ispcp is reporting: 1.25 GB (Summary)

Why awstats is reporting 0.16 GB more than ispcp traffic system?

With traffic goes up, the difference between both analyzers is getting significant:

awstats: 4.26GB
ispcp: 3.35GB

Almost a GB difference!

Anybody has any idea where i can seek for the roots of this issue.
Any help and ideas will be more than welcome.

Thank you