jumping problems

i have a collie greyhound lurcher 16 months old i live in the lake district which is great but i am having problems getting jem my dog to jump even quite small fences and stone walls which can be an issue when out as around here it is a neccesity. Can anyone suggest some training techniques that i can try. I would be grateful as he is too heavy to lift over obsticles

Start with lightweight poles that will fall easily - maybe she has rapped her legs which has put her off?

I would have a word with the vet , just in case there ois a medical reason for this, and ask if there is, ask for a referral to a canine chiropractor.
Elaine

My first thought was a trip to the vets too. She may have bad hips/ or other, which makes it painful for her to jump?