[Exchange] Send as inquiry

[J- P]

Hi all,
 
I was trying to give send as permission for a group to  a new employee via ecp, 
and was given the error;
 
Access is denied. Active directory response: 00000005: SecErr: DSID-031521D0, 
problem 4003 (INSUFF_ACCESS_RIGHTS), data 0
 
Now , using the same  admin account I entered ADUC and granted the user send as 
over that same group, what has me stumped is why would the admin account not 
have sufficient rights in ecp  and yet have sufficient rights in ADUC.
 
Thanks,