Custom Table Transaction ID Not Counting above 100

Hello Experts,

I have created a custom table, with the field TRNID with data type NUMC and Length 10.

Now,

1. The problem i'm facing is i have used a query, Which increments the number by 1.

SELECT MAX( trnid ) FROM ztbl1

                         INTO rv_transid.

     ADD 1 TO rv_transid.

But once the number reaches 99, always the query takes maximum as 99, and generates 99+1=100 in all the scenarios. For the next time it never considers 100 as maximum to generate 101.

2. In the tablei have checked the transaction ID where i have sorted the field, eventhough the it shows 99 as maximum.

I have attached the screenshot of the table. Please have a glance.