[Solothurn]

Electronic scales are sensitive to changes in barometric pressure, wind and electrical interference.
To have to rezero by pressing the zero button between charges is fairly normal.
Make sure your pan is on the scale before rezeroing each time. I found using an old pill bottle to dump my powder in, then transferring the powder to the pan that is sitting on the scale, makes for more precise charges.
Cell and cordless phones can give you goofy readings on the scale.
I did not use to believe the signs in hospitals, until I saw what they would make my electronic scale do.