Newbie...anyone want to help evaluate my first large deal?

[Steve D.]

hello, I hope to be someone who can contribute to others in the future, but now would appreciate any eyes on my first major opportunity.
8 homes in small country town...total package price for the homes is 170, but I will offer 150. the seller has had these homes for many years and wants to cash out. The tenants love this guys houses (he has over 60) and there is a waiting list for his homes. today, they are 100% rented with my long term tenants (over 10yrs). Home conditions are 'good'..most he has updated with central air and very good maintenance. What I love is the monthly rent income is 3200 per mo. I have calculated PM fees, general maint, ins and taxes. I would finance 75%, meaning my cash in is 40k. By all reasonable estimates my pre-tax annual rent is $20k. Reading other posts I feel good about the 2% rule here, but for some reason the IRR calculations don't like this deal..So I am confused, to me, I am putting in 40k and earning $20k annually...How could this NOT be a good deal? What am I missing here? FYI, I am not banking on appreciation and assuming 95% occupancy
Any thoughts greatly appreciated!!!
thank you