Horizontal Velocity Time Series

Hello! I'm running a W2 model for a lake in Brazil that has been calibrated for hydrodynamics and temperature. However, I want to output the time series for horizontal velocity, in order to get Reynalds medium values for the lake, but when i try to extract them it returns lots of "-999" values. What does this means? Usually "-999" indicates lack of data, but how do I correct this? Cause there's no indication of any running error.. Any help would be great..