PowerPivot DAX Measure to Dynamically Calculate Rolling 12 Months

[bravo1563]

Hello
I have a unique problem, each month I have a new 12 month forecast. What I need to do using a DAX measure is sum last period of each official forecasts with a 1 month lag for each official forecast. In other words in the below example if I'm filtered on MAR 2017 I need the measure to sum all of the bolded red values which equates 554. Please note this is not in a regular calendar months but in a unique fiscal dating. But if we can write the measure in regular calendar time intelligence I should be able to convert to proper time periods. Any help would be greatly appreciated, thanks!!

Official Forecast	DEC	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV
MAR 2016	43	38	14	60	64	18	38	35	53	86	18	58
APR 2016	77	66	73	99	79	84	53	40	13	16	54	16
MAY 2016	40	74	10	18	40	43	32	35	17	40	36	2
JUN 2016	44	21	64	5	84	54	88	69	91	89	23	79
JUL 2016	18	96	37	59	22	45	22	3	69	80	67	22
AUG 2016	32	1	30	52	2	51	65	76	68	42	58	17
SEP 2016	5	5	36	57	87	12	72	27	43	77	26	26
OCT 2016	47	33	88	67	80	19	4	90	39	23	1	7
NOV 2016	85	48	41	58	5	80	39	82	90	50	56	84
DEC 2016	6	75	59	42	11	47	20	90	13	29	39	31
JAN 2017	18	1	90	65	84	8	85	80	77	4	85	54
FEB 2017	46	78	64	59	4	18	66	3	76	1	27	69
MAR 2017	50	29	21	57	1	52	41	29	1	47	48	76

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[Matt Allington]

I'm sure this can be done, but I don't really understand the scenario. What do the columns refer to? What are all the othe numbers that are not bold red?

I'm pretty sure the table needs to be restructured. I would have a long thin table like this

scenario. Period. Forecast
Mar 16. Apr 16. X
Mar 16. May 16. y
Mar. 16. Jun. 16. Z

etc

thne join the period to a calendar table and use the scenario to filter the scenario you are looking at.