What's my real profit?

[Chuck Astleford]

I am considering putting an offer in on a duplex.  The financials are as follows:

Rent charged $1400 total

Mortgage(land contract monthly payment) $300

Taxes $109

Insurance $72

Mgt Co $120

Utilities (landlord pays one side of utilities) $200

Maintenance $140

Vacancy $140

Cost to payback my $ back to me for down payment $231

Total cost of $1312 each month 

That means I'll make $88 a month if everything goes as planned (which it won't)   My question is what am I missing here.  The cost of the land contract monthly payment is only $300 per month and rent is essentially  $1200 because 200 covers utilities.  so that is a $900 difference.  I feel like I'm not using a correct assumption with something.  Any guidance would be helpful.  TIA  Chuck