purchase order issue

I have loaded a delta in to inventory cube.it appears that the problem of isolated instances of 3500060401 purchase orders being changed by biw.

an example of this 3500060401. it has 6 records line 1 for $7.15 has been changed, where as other lines are not affected.

first record in r/3 is $7.15

in bw it comes $7.15- -sign is comming.

what is the problem

please give me reply ASAP.