Shorcut from Lumbridge castle to collecting Tear of Guthix.

I did finish the quest Lost Tribe, but I still cannot use the shorcut at basement of Lumbridge Castle go through swamp cavern to collectin Trear of Guthix.
Message appear every time when I want squeeze the hole, even I use all type of pickaex on the hole but nothing happen.
Did your guys have any idead?
Thanks.

Thanks. I tried all type of light source....but still not work.