Feel like I’m missing something in DQ II HD 2D.

For some reason I’m just stuck. I don’t know if I missed some key piece of info from the mermaid queen or something but basically I finished Mersea and the mermaid sanctuary I have Lorelei’s harp and I spoke with the over seer and the other fairy about the memories. The mermaid queen marked on my map Mariellas location. But for some reason I cannot use Lorelei’s harp at all. Every time I try to use is greyed out. And if I try to use it, it says nothing happens. I have the star, moon, sun and water sigil.

Did I miss something? Feels like I can’t really progress without being able to use Lorelei’s harp in other parts of the map. Thanks in advance for any help!