too small fitted sheet

I wanted to put the sheets in the crib next to me in my maternity chicco back there and impossible to put the fitted sheet on the mattress! In addition I had bought in advance following a promo then not possible to refer, it does not come to the idea of ​​trying to reception because it was unimaginable to the look and these are sheets provided expressly for this bed! So for me unnecessary sheets heureuseusement that I had made make other measure!