Help regarding Cash Position and groupings

Hello Everybody,

I am encountering a problem regarding cash position. I already defined in FS00 all the necessary information needed, like planning levels, ticked cash flow relevant etc. I also made a posting via FB50 to these GL accounts.

I am not quite sure though how to create groupings? I created one via OT17, but when I was about to create, it said it doesn't belong in table T038P. So what I did was use a standard grouping, but unfortunately that didn't work. When I ran the report FF7A, it said "NO DATA SELECTED". Please help. I am new to cash management. Please comment if the procedure I did was correct. Thanks