I got the following message: Can I still report the estimates as valid? Thanks very much.
THE MODEL ESTIMATION TERMINATED NORMALLY
THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES MAY NOT BE TRUSTWORTHY FOR SOME PARAMETERS DUE TO A NON-POSITIVE DEFINITE FIRST ORDER DERIVATIVE PRODUCT MATRIX. THIS MAY BE DUE TO THE STARTING VALUES BUT MAY ALSO BE AN INDICATION OF MODEL NON-IDENTIFICATION. THE CONDITION NUMBER IS -0.129D-15. PROBLEM INVOLVING PARAMETER 19.
THIS IS MORE LIKELY DUE TO HAVING MORE PARAMETERS THAN THE NUMBER OF CLUSTERS MINUS THE NUMBER OF STRATA WITH MORE THAN ONE CLUSTER.
The number of clusters minus the number of strata with more than one cluster is the number of independent units in your analysis. You have more parameters than independent units. The impact of this on your results has not been studied. We give this as a warning.