GR Creation for Schedule Agreement

I am facing problem in GR creation for Schedule agreement. When I am creating GR, it is telling no items exists even though Schedule agreement & schedule lines maintain for that. Some times when they are many lines and if we do GR for one line automatically all lines disapper and won't come stock or don't show in schedule lines.
I am in 4.7 version.

Please check whether you have attached SA in the source list with line items.

The following are the steps in 4.6B.

T-code:ME01
Enter Mat.code & Plant.
In the next screen pl.do the following:

Valid from - commencement date of the SA
Valid to - End date of the SA
Vendor - Vendor on whom the SA is released
POrg - Your purchase organisation
PPL - Leave it blank(This is only for interplant)
OUn - Ordering unit
Agreement - SA number
Item - 1
MRP - 2 - Record relevant to MRP, Schedule line generated automatically

If you are having several items in one SA,you have to do the above repeatedly by giving the 'Item'1,2,3 etc.in each line.
Then run MRP.You will have the sch.lines and you can receive the materials without any problem.

If you have already done the MRP, pl.maintain the sch.lines in ME38 by selecting each items.