Pest Control--Mice--Not taking the bait!?!?!

[Jacobus Rex]

Hi, 

SFR in Minneapolis. Tenants have complained of mice, three different times over 5-6 years. I've had local well-known pest control company there three different times, at least. Still in the last year tenant complained of droppings. He wasn't afraid to go after them. He set lots of traps with peanut butter and cheese and the gel stuff such as the Tomcat brand. He caught one mouse. Still saw droppings. This person had very good hygiene. The house was clean. As in the past, these buggers wouldn't take that bait.
QUESTION:  How is it possible they wouldn't take the bait?  Consistently over years.  Once in the house why wouldn't they take the bait.   Frustrated. 

[John Warren]

@Jacobus Rex I am dealing with this issue now at a building I own in Berwyn, IL. The area is very urban and we are dealing with the rat issues from Chicago which are very real. The answer is not to catch them in traps, but to eliminate the ways they can get into the building. Check the perimeter of the building for holes and fill them with steel wool, expanding foam, etc. It can be an ongoing war, but eventually you will win when there is simply no way for them to get in anymore.