Emission Inspection failed because machine does not get any data from car's computer
 

I have a 02 Tribute LX. First my engine light came on. Autozone diagnosed that it's the DPFE sensor so I replaced it. I then disconnected and reconnected the battery to turn off the engine light and everything is fine. The next day I took my car to Jiffy Lube for a car inspection but after hooking up to their machine it said "not ready" since I just unplugged my battery a day before. So they asked me to drive it for a few days so that there is enough data for the machine to read. Well, I drove it for a week (about 150 miles) and took it back for a second inspection. This time they said that their machine can't read any data from my car's computer. They told me to take it to the dealer to check it out but I can't afford that for now. I checked all the fuses (including the one for the Data Link Connector) and they are all fine. I even took it to Autozone and everything shows up fine when they hook their diagnostic tool to my car's DLC. What is the cause for the inspection computer not to read anything from my car's computer? You help is greatly appreciated.

RE: Emission Inspection failed because machine does not get any data from car's computer
 

Just took it back for another inspection and this time it passes. I don't know how it worked this time because I didn't do anything to it but to drive it another 50 miles. Guess the computer was not ready at 150 miles but ready at 200 miles. Thanks anyway.