In general the iisfind feature of CPLEX 12.6.1 is working properly -- you can see some typical output for a MIP in the attached listing. Thus you may have run into a bug that is specific to your situation. Large exit codes like 3221226356 don't have any specific meaning and usually are a sign that something unexpected has happened.
As always, it is a good idea to add 'mipdisplay 2' to your cplex_options string to see whether CPLEX got started at all, and if so, what it did before terminating; that might suggest a workaround. If you continue to encounter this problem however then please send us some files that we can use to reproduce it on our computers; that is the key to finding the cause and getting it fixed.
Bob Fourer
am...@googlegroups.com
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