not equal in set expression

[upaliwije]

I have following expression which is working fine

sum( {<R_YEAR=,R_MONTH=,[R_MONTH]= {$(=concat([R_MONTH],','))},[R_YEAR] = {$(=max([R_YEAR]+1))},POL_TYPE={'R'}>} [PREMIUM] )

But one I modify it in the following way it does not work

sum( {<R_YEAR=,R_MONTH=,[R_MONTH]-= {$(=concat([R_MONTH],','))},[R_YEAR] = {$(=max([R_YEAR]+1))},POL_TYPE={'R'}>} [PREMIUM] )

Pls help me write it correctly

[upaliwije]

Dear Friends

Could you pls help me to rectify my expression

[kaushiknsolanki]

Is there any selection you are doing which will impact the calculation?

If yes then those needs to be neglected in the set analysis I gave you.

Regards,

Kaushik Solanki