Rollup Text data to the parent member "YearTotal"

Summary:

Content (required):

Hi All,

I'm entering employee position ID data (as Text data type) in the lev0 period members (Jan,feb,mar etc..) and want to see it is being rolled up into the "YearTotal" parent member. Eg: If I enter Position ID P000001 in Jan, Feb and Mar, I'm expecting to see P000001 rolled up into "YearTotal". But it seems even though I run the standard "OWP_Rollup" rule, not being rolled up into the parent member. Is there any specific way which I can rollup text data to a parent member? Appreciate your help to achieve this.