Adding Locator Control To Existing Items

Hello,

I have a question about locator control on Oracle EBS. Is it possible to have locator controls on items that are already been created or is this only possible on newly created items?

I am trying to add locator control to a specific item so that it can only be put into a specific locator. However when creating a miscellaneous receipt, the locator option is grayed out. I also try to change locator control to pre specified on the item and it did not let me due to the item already being in the system. However when i tried this on a item that was new and had not had available or on hand quantities, the locator control options where enabled and i was able to change the control to pre specified.