what happen at my VFP.

when i run my program, i can edit data in GRID1.COLUMN1
( GRID1.COLUMN1.RECORDSOURCE = COMPANY )

but, i can't edit the COLUMN1 today. then i try to create another GRID include same field. it's can't edit too.

BUT I FIND THAT, IF I ADD THE ALIAS WITH FIELD NAME AS BELOW :
( GRID1.COLUMN1.RECORDSOURCE = BUYER.COMPANY )
THE DATA CAN EDIT AGAIN...

why ??