Problem Fixing Shelves When Drilling Holes

[Symun23]

Hello,

This is my first post so go easy on me,

I am trying to put some shelves up in a bedroom, but I am having problems. When drilling the holes I can only get about 1cm into the wall before I hit metal. The wall is the dividing wall between the two terraced houses. Does anyone know what this metal might be? And how would I get round it?

Also just on a side note the shelves I was going to put up were going to be stepped, each shelf would have three screws, I have tried drilling the holes for all three shelves and for the middle shelf two of the three holes have gone deep enough but the top and bottom shelves none of the holes have gone any deeper than 1cm.

Any help would be appreciated.

[welsh brickie]

unsure of the steel unless it was a metal studding against the wall to insulate it. If its plasterboard then use redi drive fixings. If its not try self taping screws for metal studding