Having trouble calibrating my grains digi-scale

[highpoint forge]

I picke up a small digital jeweler's scale off the auction site and it arrived today. I followed its directions to calibrate it and kinda had to guess at some points, as there were no instructions. Guidelines were printed on the inside of the lid. I could not get it to register "zero"  with nothing on the tray, before calibrating. It kept reading -34....

Weird, so I followed the rest of the calibration steps even though I didn't start at zero as required. My 100 gr brass inserts are 99 grains or 98.7.

Anyone have skills when it comes to digi-scales?

[Buckeye Trad Hunter]

It should have came with a 100 gram calibration weight.  If it is like mine it will need to be calibrated in grams instead of grains.  Does it have a tare button to get it back to 0?  Did you use new batteries?