By the way: as I see, the images are located on “www.reachsuite.com”. Very often servers have different external (Internet) and internal (intranet) names. “www.reachsuite.com” looks like an external name.
It is not always true, that the servers within intranet are able to resolve the external names or to establish a connection using the external name.
Just to make sure that it is not your case, try to temporarily substitute “www.reachsuite.com” in the image URL with its local IP address.
Also pd4ml.enableDebugInfo(); forces PD4ML to dump connection statistics to STDOUT (or server’s log), which could be also useful to analyze the problem.