SUM MAX DATE - for Previous Month when NULL

[Chloe19]

Hi all 

I am new to Qlik Sense, have a pretty basic question when it comes to an expression.

I am trying to sum data from the previous month and I have the below code which works:

• SUM({<[MONTH/YEAR] = {"$(=Date(MonthStart(Max([MONTH/YEAR]), -1), 'MMM-YYYY'))"}>} TRANSACTION)

However, a dimension can be null so I have the below, which also works

• num(sum({<Region_Name={'*'}>} TRANSACTION),0)

My problem is, how do I combine them to show me the transaction for the previous month using the last dot point.

So how do I put point two into point one?

Thank you for any and all assistance 

[Digvijay_Singh]

I don't know the actual need but multiple set conditions in AND mode are written like this..

SUM({<[MONTH/YEAR] = {"$(=Date(MonthStart(Max([MONTH/YEAR]), -1), 'MMM-YYYY'))"},Region_Name={'*'}>} TRANSACTION)