Try

lcMonth = UPPER(RTRIM(s_month))

>i am trying to change with these codes, but month is also replacing with 01/01/01.........all year is changing correct.
>

>lcMonthList = "JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOW DEC"
>*lcMonth = "JAN"
>*lnYear = 2009
>
>SELECT registration
>GO top
>scan
>lcMonth =s_month
>lnYear = year
>newdate= DATE(lnYear, INT(AT(lcMonth, lcMonthList) / 4) + 1,1)
>replace sdate WITH newdate
>endscan