Hi Mani! Sorry for the holiday delay with the reply.
I would recommend to check the following:
– I guess PD4ML runs on a server. Make sure the server (not a client browser) can resolve test4.j.layershift.co.uk DNS name and has a routing to it. Log into the server and try to load any test4.j.layershift.co.uk URL with wget or anything similar.
– If the above is ok, check logs of test4.j.layershift.co.uk if there were attempts to load the image by PD4ML and error codes (if any).