How to populate Data automatically with valueset in DFF

Hi,

We created one DFF, when user selects Customer Number from one LOV, the immediate customer name filed should populate name automatically in DFF.

The requirement is, Customer Name should be defaulted automatically as soon as User enters Customer Number.

But now  have to select the LOV of customer name explicitly.

Please give the inputs to solve this issue.

Regards,

Aravind M