IDS 7.3 help needed ASAP

Hi , Here is the problem in detail : We have an informix 7.x database and users connect to it through a c++ application written way back in 1998. The issue is thats ,i have granted myself DBA role,resource and connect privs and i am still unable to connect to the database using the application.I sepecifically granted all privs on all tables to my OS login id in the database , i can see all the privs but i am still unable to connect to the database. Is there a mapping that i have to do in order to see the data.by the way this is a windows 2000 server and i have admin option on this server. Greatly appreciate a detail description of whats going on here, I am a begginer to the Informix . Thanks and regards, Alex Addanki