Error when executing ad_zd.grant_privs

Hi,

When we try to execute the grant script on custom objects, the API gives the following error - 

ORA-01031: insufficient privileges

ORA-06512: at "APPS.AD_ZD", line 1156

For example, the following command gives error (Custom table)

EXEC ad_zd.grant_privs('SELECT','L3AR_ACCRUAL_DATA', 'L3DWSTAGE');

But the following command does not give error (Standard table).

EXEC ad_zd.grant_privs('SELECT','HZ_CUST_ACCOUNTS', 'L3DWSTAGE');

Note that the custom table was upgraded using the API ad_zd_table.upgrade