Signal levels

[RimaNTSS]

Hi! Before reinstalling images, couple of weeks ago I took all signal levels from all frequencies on 28,2*E, was happy about results. Today I installed last VIX image, and feel that all levels went down for up to 15%. After scanning getting same number of channels (about 950). I am almost sure that antenna and LNB tuned exactly same. My question is: Was something changed in new images, so signal levels showing less than before?
Or, I should better go and try to tune antenna?

[RimaNTSS]

Everything is not so bad, weather conditions are much better today. Rescanned all 87 frequencies and got good reception (even better than it was before software upgrade). So, software is not guilty but weather.
This is on T90, location- Brussels.