what is your age?
in the radial head # cast should had been applied.
movements should not have been tried at least 4 weeks of injury
but since you are trying for the movements from 2nd week only and no plaster was given there may be a possibility of displacement of fracture
which may lead to inability in movement, although restriction may be due to fracture per se also so get an x ray
elbow immediately (AP and Lat view) to see the current status of fracture. after this you may review, i will be here to reply your queries.