Does a promotion affect the PERM processing and Why?

[san.adi]

Hi,

I'm currently a H1-B visa holder and have an approved I-140 from a previous employment. I've been in my current job for about 1.5 years now and my GC process was initiated by current employer and I'm almost done with my PERM process. I recently got promoted and I was informed that the company will have to redo my PERM process as per the immigration regulations. Is this true and if so Why?

Does this also hold good for other stages during the immigration process? Like I-140 etc or is this only applicable to the PERM process? 

Thank you in advance.

[JoeF]

The LC is for a particular job. If you get promoted, the job obviously has changed, so the PERM has to be started over for the new job (I doubt that you would go back to the old job, essentially a demotion, when the GC is approved.)