Material column is empty in VF04

Hi,

In the material field of VF04 is not showing anything. What i have done is i goto SE11 -> put VKDFI under database table. Then under component tab, i put in a component MATNR and activate it

Goto VF04 -> execute. In the maintain billing due list, the material column already showing there but the field is empty. There is no information showing.

What i did wrong? Do i have put in some coding in SDBILLDL?

Thank you