Oracle Database Discussions

Hi guys,
i've try to use opatch utilities with oracle db user but when i launch it shows me this err:

OPatch failed to locate Central Inventory.
Possible causes are:
The Central Inventory is corrupted
The oraInst.loc file specified is not valid.
LsInventorySession failed: OracleHomeInventory::createInventoryObj() gets a null OiicStandardInventorySession object

I've find that Central Inventory is wrong, because it's set to Grid Agent Home, look follows:

Central Inventory : /home/oraagent/oraInventory

so, someone can says me how i can change Central Inventory for correct this problem?

thanks very much
Andrea