Create an arc with two points and the radius

Hi,
When I try to create an arc with two points and the radius it doesn't seem to work.
When I select the first point it's ok but it doesn't take the second.
Can somebody help me?
Thanks

There is no tool for arc with two points and radius.
Do you mean circle with two points and radius? You have to set the radius in the Tool Options bar above the drawing area.
 

Yes I meant a circle. Well, I simply put a radius too short compare to the distance of the points.