Copying data using F4 key for WBS element in CS71 & CS72

In SAP, data for any field can be copied from the searching criteria by using F4 key or the icon on the right side of the respective field. Say for opening any project, you use open icon in Cj20n, then system ask for the PD / WBS / Network, then you put the data directly if you know or you can get it from different searching criteria using F4 or the clicking on icon on the right side of the respective field.

Bu it is not happening partculraly for WBS element field in transaction CS71 & CS72, why ?