Amit,
The warning in the log is just indicating that the iterative maximum likelihood optimization method for fitting the model failed to find a solution. As with any optimization program, this can happen for some models on some data sets. The message suggests some ways you can change the optimizer which *may* allow the procedure to find a solution. In fact, if the procedure does not converge, it presents the results based on the last iteration. This is not the maximum likelihood solution, so you may not even want to use the results. To fix the problem, you can try the suggested options. If they don't work, you may have to change your model... probably by reducing the number of parameters in it.
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