Set Analysis counting value instances from prev month to this month

[#1]

Hi,

New  to Qlikview and after help for set analysis.

I has data set like below;

Date                CustID
1/08/2014          1

1/08/2014          2

1/08/2014          3

1/08/2014          4

1/08/2014          5

1/09/2014          2

1/09/2014          3

1/09/2014          6

1/09/2014          7

1/09/2014          8

Id like to count where custID is same from Aug to Sep (i.e. 2) how many custID repeates there are.  So result from above would equal 2 (i.e. 2 and 3 appear in oth months.  I have 2 variables covering dates  $(vThisMonth)=1/09/2014 and $(vLastMonth)=1/08/2014.

Thanks in advance,

Jason

[#2]

Thanks Anbu.

Apologies that's a typo on my part.  The format for dates in variables is definitely DD/MM/YYYY.

I directly copied the formula you've posted above.  Got the below  error;

"Error: Error in Set Modifier element function set"

That's bad right? 2 Errors!!! 🙂