SET analysis with maxstring

[#1]

Hi,

i'm doing a set analysis below, but i have a problem at &.

someone help??

FLAG_VAL = {'M-' & $(='MaxString({$<PROD={'ACTUAL'}>} SubField(FLAG,'-',2))') }

Thanks,

[#2]

thanks vincent... in the end, i changed the data structure... otherwise i guess i wont have solution to it.

Thanks for everyone's help. have a nice weekends.