I don't know what you want to do, but please check the example below.

For example, if you want the field “Storage date” [RECEI->DTSTORAG] to appear and disappear as the logical field “Stored”[RECEI->STORED] is selected, it is necessary to define the condition ”Show when” of the form field [RECEI- >DTSTORAG].

In this example, the condition of “Show when” is “emptyL( [RECEI->STORED] )==0” (see images below)