I tried to make a Logistic Regression in order to explain forest cover changes (Permanence, gain and loss) with four independent variables (Slope, Distance to water bodies, to roads and to settlements). I set the variables in the Logistic Reg window, but in the step 3 of 6 3%, the analisys seems to stop and a message appear: A singular matrix has ocurred. No meaningfull regression coefficients found. Adjust the combination of the independent variables.

What it mean this?