Dear Sir, Why the RPEM sub model can not be selected? I mean the RPEM sub model cannot be selected as “simulate” when I click the confirm button, it will restore the option"do not simulate…". the newest version7.2 trail version Are there any preconditions to use it? Thanks Wang Attached files 
The prerequisites are temperature and water quality sub-models. If they on and RPEM still doesn’t work, can you send us your model so we can look at it (just model input files in a zipped folder)?
We have looked at this and it appears to be a bug. Thank you for notifying us of this. We will provide a new release of EE7.2 next week which will fix this issue.