MAXPL , STDEV

Hi, I have two questions and will be thankfull if any of you knows how to solve the following questions.

1.

When modeller runs on a moltiple alignment it sometimes does not generate a model and gives the error : Increase MAXSPL to at least 630 ERROR_STATUS >= STOP_ON_ERROR: 1 1

If i understand correctly this error occurs because the models that are imposed by the given alignments are not superimposable. This probably happens because of some fragment/s in one or more of the alignmnets. I prefer not to model that part at all than to increase the value of MAXPL.

Is there any way i can deduce from the log file which a.a's i sould delete so that this error will not occur ?

2. I sometimes get the error STDEV < 0 What causes the standart deviation to be smaller than zero ? How can i correct such an error? that is , how can i know what parts of the alignmnet i sould remove , or anything else ?

Thanks alot! Iris.