seller financing structure

[Matt B.]

I'm looking at new deals and I'd like to acquire one of them via seller financing(SF).  Get SF from the owner wasn't the hard part, especially if they've had some sort of motivation.  But the last time I took it to the banks with 20-30% SF, the lender(s) didn't allow a 2nd position on the property, even if they were in first position

Is this a common occurrence, lenders not allowing others, more specifically owners providing SF, to take a 2nd position? 

Am I structuring it incorrectly?  I thought 65-80% lender financing + 20-35% SF would be suffice.  Or is the structure fine, but its just more of a numbers game and I need to find the right lender?