Eprom problem

[99 speed 6]

I have recently put a new (E6538) oil pressure switch on my 99 Speed six cerbera from a dealer and since then the readings on the laptop software has gone crazy from 104 PSI to nothing. I have checked the internal gauge on the dash and it is spot on with good pressure. I have been given an updated eprom which is a 2FOO5F old one is (2F2BBE) but when I install this it comes up with no configeration loaded.
I have been given the information from a technical bulletin from the factory from March 2000 no 139 that you have to install the updated eprom chip to get consistant idle oil pressure readings.
Can anybody help?