blinking humidity guage reading on Avallo Accumonitor readout?

[wgp]

My Avallo Accumonitor humidity readout was flashing at a value of 99 (the right side, which I believe is what one wants as a humidity vs the actual reading, but I may have that reversed). My back-up hygrometers inside my cabinet were reading at 65%, however. So I suspect that 99% value was NOT actual.

What does the flashing light mean? I did add water, as it was low but certainly not out (maybe 2" left in the water reservoir).