simple tissue ablation model

Hey all,
Im trying to set up a very simple ablation model of cardiac trouble and am having trouble

the model is a simple 2D axisymmetric geom consisting of a square with a small rectangular electrode section substracted from the bottom left corner.
All im trying to do is set the electric current to 25V on the 2 electrode boundaries and view the temp profile across the rest of the tissue, although im struggling to get it to work properly .

Any help would be much appreciated