Recently I have been receiving the same error message, "Data Error", when I try to run a regression via Gretl. OLS, Heteroskadasticity corrected and all other regressions seem to work, however Logit and Probit do not work with the data set I have. There is 571 points with 4 independent variables, however I have successfully run a Logit regression before using the same data set but with more points. Perhaps there is a minimum amount of points, or that somehow my data got out of wack?