我在做多元logistic回归的时候，出现了这个warning，请达人指教，这是不是说明我这个回归不成立呀？谢谢了

Warnings
Unexpected singularities in the Hessian matrix are encountered. This indicates that either some predictor variables should be excluded or some categories should be merged.
The NOMREG procedure continues despite the above warning(s). Subsequent results shown are based on the last iteration. Validity of the model fit is uncertain.