Stuck after 'The Greedy Captain' *SPOILERS*****

So I killed Garcia and I talked to Alvarez and I know I need to summon Captain Steelbeard again and talk to him to find out where the Water Temple is, but for some reason I cannot summon him with the Skull Sceptre anymore. He is no where to be found on the Island of the Dead, and I cannot summon him either in the underworld or real world. Is this a glitch? Can someone help me, perhaps I am doing something wrong. Thanks in advance to anyone who can help!