How to increment a character variable?

Hi,

I need to increment v_chgno by 1. But the following code gives me runtime error. Please can anyone guide me where i am going wrong.

Data: v_chgno TYPE char12 value 'CR0000000000',

v_newchgno TYPE char12.

v_newchgno = v_chgno + 1.

Thanks in advance.

Sunanda.