I was in the same situation, some times it picked up all some times missed some and then would loose it later on. put in a repeater under the basement and now they can be picked up over 200 feet away can have the monitor in the house and check tires. did not want to spend any more money but was well worth it. try setting the monitor next to the non reading tire.
Ed So.Calif
1950 Ford F1 street rod
1968 Baha Bug with 2.2 ecotec motor 170 hp, kingcoil
2000 National Sea Breeze 5th wheel trailer
1998.5 Dodge 2500 4x4 Cummins,4.10 gears,turbo,trans,injectors,oil cooler,lockers,edge EZ, 35" BFG's, air dog lift pump etc.