Last sword & glass piece.

I am unable to pick up either. When I try the scene disappears!
What am I doing wrong? (It isn't because I have placed one symbol at the base of a statue too early is it? - if so how can I undo this?)

OK - worked out problem!! again!

just in case someone else out there has a question about this... look behind the crates in front of the broken window... lying on the floor behind the crates is a sword and a piece of the window... good luck