Calculating results of solar collector and Energy Recovery Ventilator are 0

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In my OS model, I've added solar collector in Hot Water Plant Loop and Energy Recovery Ventilator in OA Air Loop, however the energy generated or recovered by these two models are 0 in the final calculating results. I couldn't figure out why it happened. I wanna attach my OS file in attachments but I couldn't because of my low hierarchy. Could anybody help me find the problem. This is very urgent and thank you so much.