Travel Cot (Vauxhall SW8)

Cot hasn't been used much and condition is very good, however we can't make one side of it lock as can be seen in the photo. Size is 102cm (L) x 74cm (W) x 77 (H). It has the usual base of a travel cot and we also have the mattress to go with it. Before it goes to waste, perhaps someone knows how to make it work/fix or lock the side and can put if to good use.