Scheduling agreement,(GR value is wrong)

I have one scheduling agreement, the price is 1.31 INR from 10.10.2007 and i made GR for this three times, it shows correct quantity and value in Purchase order history, in 18.10.2007 the one GR is showing me wrong value, per material isit, showing me 0.02 INR why?(we are putting the quantity is correct)

for the vendor and material Inforecord is existed in that, also 1.31 per item is there, and validity of inforecord is up to 9999 year.

what must be the reason,

i have checked any body changed the value are not, but they have updated that from30.10.2007 they made value 1.32 Inr per material

what are reason?

sapman