I have a hotpoint CSX22GRBKWW side by side fridge. Frost started showing up on the back freezer wall and inturn caused the fridge to be warm. I ordered a new Defrost control timer (16 hours 35 minutes. Part Number: AP2061695 made by GE) and Defrost heater Assembly (Original GE Part. Kit includes defrost heater, wire harness, and defrost thermostat. Do not order def. thermostat in addition to this kit, unless you need a spare one. Part Number: AP2071523 made by GE)

Today I installed the new defrost control timer and the fridge wouldn't turn on. All the numbers and specs on the new and original unit match. If I put back the original defrost control timer the fridge turns on just fine. I went ahead and replaced the heater assembly - the original was all black like a burnt out light bulb. I guess I will see if the frost starts to show up again. Is there anything I need to do for the new defrost control timer or is it just possible that i got a new defective part? Should there be anything else I should be checking that may cause frost to build up?

thanks in advance.