Like apples, pears need a different cultivar to pollinate them. The other tree needs to be in the same pollination group, i.e. flowers at the same time. If you only have the same two types of pear, then they won't pollinate each other and you need to rely on them being pollinating from a neighbouring pear tree in the same group. So if there isn't one nearby they won't be pollinated and they won't set fruit.

thanks for that myron. i have had a good look at both trees+there is a few pears developing on both trees.when there were strong winds. most of the flowers were blown off, the same as last year, i bought both trees because they are self pollinating types

It seems like your trees have been pollinated then. If my memory serves me right Concorde is a late fruiting pear, so there's time yet.

Even if a pear tree is self-pollinating, it will perform better when another pear tree of a different variety is present to cross-pollinate it, so it's always better to plant two different varieties of the same pollination group together for a greater success bearing fruit.