SAP Note 19870 - Selecting an initial field value with F4

Symptom:

The possible entries for a field (e.g. from a Customizing table) are to be displayed with F4 on a self-defined screen of a customer development. This table has a 1-place character key whose value can also be blank. If the value "blank" is selected via F4, the value is not copied to the screen field; instead, the previously entered value remains.

Cause and prerequisites

Copying initial field contents via F4 possible entries is not supported.

Solution
None available.