This table shows customers order lines so I want to count the number of order lines using ItemNo for rolling 12 months.
I tried several solutions that I found in this forum but it doesn't work since it shows just the no of order lines for each months. I'm using calendar and btw it doesn't shows the months with 0 order lines, also something that I couldn't fix.
If you use MAT as the dimension and do Count(LAART) as the expression then you should get the rolling twelve month total in each cell.
By selecting a single month, over 12 months old, you should see that it appears in the following 12 MAT months, and similarly if you select a single MAT month you should see that this includes the preceding 11 months.
Personally I would add 1 as OrderCount, to each order line in the load, then the expression in the table becomes sum(OrderCount). It should give you the same result as Count(LAART), but it should be slightly more efficient.