In a recent security update (December 14, 2015), Apple implemented a security measure that disallows the ability to remotely click Keychain Access windows (synthetic clicks). For instance, if you are remotely assisting a customer with retrieving a password, upon opening a Keychain Access entry, you wil not be able to click Allow or Always Allow in order to reveal a resource password. The user will have to click locally. This can also be especially troublesome if working remotely on a headless server as there may be no local user to assist.
Reference: https://support.apple.com/en-us/HT205375