Hi Husin,
it seems that rfcexec can be run from the command line without errors.
please also check:
-run a connection test on the app2 from SM59 on SERVER_EXEC
-check if there are any incompatible rfcexec.sec files on app2
(For example, remove (rename) the rfcexec.sec in the home folder of the <sid>adm user)
Thanks and best regards,
Shi Feng