Upgrade error : Not mutually convertible

Hi All,

I am doing upgrade from 4.7 to ECC 6.

I got error in one program as shown below.

A line of "IT_PRD_COST" and "L_PRD" are not mutually convertible in aUnicode program. .

Actually declaration for these are shown below.

data:  l_prd(200) type c,

data: begin of it_prd_cost occurs 0,
        matnr type mbew-matnr,
        date(10) type c,
        cost type mbew-verpr,
      end of it_prd_cost.

And code is

insert l_prd into it_prd_cost index 1.

How to rectify this one.

Regards

Jai