did have a minus difficulty is a problen in this miner?

btw I've been mining MINEXCOIN for 3 days

I often get minus difficult and directly decreases my hashrate on my pool

like this http://prntscr.com/kb8rhx and this http://prntscr.com/kb8ryf

i have 4rig AMD using 0.4 LOLMINER and 1 rig NVIDIA card using EWBF

each AMD rig got 65 kh/s on LOLMINER but got average 40khs - 50khs on pool chart

each NVIDIA rig got 40khs on EWBF and got stable 39khs - 41khs on pool chart

you can see this pic http://prntscr.com/kb8usl

is dev know about this? love this miner because light to windows, but this miner need more attention and upgrade from developer