help needed on legend of zelda spirit tracks

Hi. Im on the part where you have to find the linebecker treasure but i can seem to get it. Ive tried playing the song of discovery but it doesnt work. I think a spade is needed but i dont know where to get it help pls.
p.s.
this is pretty far into the gamethanks

https://www.romulation.org/forum/index.php?topic=28828.msg498296#msg498296

i dont know exactly when, where...yes. but you also need the song of light, -if im right

Go to the place where the 2 beams cross eachother.
Then go 4 steps up and 6 left.
Play song of discovery and there will pop a chest out the ground.