object dependency is empty

Hi

Can anybody clear my doubt/problem issue.

During parsing of a pl/sql block, Object dependencies are not listed in v$object_dependency view when bind variables are used .But object dependencies are displayed when values/literals are passed on to it.

Version :12.1.0.2

Dependencies are not displayed :

DECLARE P NUMBER; BEGIN A:=TEST(:VAR);END;;

Dependencies are displayed :

DECLARE P NUMBER ; BEGIN A:=TEST(:10);END;;

Thanks