[Ipopt] If statement in objective function

[Gregory K.]

Hi all, 
 
I am new to this list and I hope it is still active, and I will be able to find knowledgeable folks around here.
I have the following, hopefully easy question.
After some remodeling of my model I've realized that it would be much 
much simpler and contain much less variables and constraints if IF 
statements are used. 
I was successful in rewriting the model but now have a problem with AMPL\IPOPT solving it with IF statements in objective function. It returns all zero solution if IF statement is used in objective function
My problem is NLP, but in the future might be developed into MINLP. 
Is there some IPOPT option that I have to use? Or maybe it's not possible at all (I hope not). Am I missing something?

Cheers, 
Greg 
 
 
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