Positive injection rate with MNW2 but configuration defined with a negative pumping rate

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Dear all,

I am running a model with modflow-lgr-2 with pumping wells and keyword MNW2. 

Pumping wells are defined and activated in the parent and child models, with a negative constant value during the stress period for both. 

When I check the volume budget, budget is oK for the parent grid (.lst file), but not for the child (In the child.lst file, I observe injection of water through the wells (volume in front of MNW2 >0 in the IN column).

 

I do not understand why. 

What should I check and change in my configuration? Any idea?