502 proxy error using iControl via Enterprise Manager

Trying to start with just getting the device versions, similar to this example - https://devcentral.f5.com/wiki/iControl.Perl_DCO_EM_proxy.ashx

I can get the list of devices just fine from the EM. I can get the context_id from the EM When I set the context to the IP address of the device, I get back "OK"

But, when I try to send the get_version command

$resp = $soap->uri("urn:iControl:System/SystemInfo")->get_version();

What I get back is:

502 Proxy Error at f5-em.pl line 98.

Line 98 being the line in the perl script that is shown above sending the get_version.

I know I have connectivity to the EM, I know I can set context, and I know I can do 'get_version' if I go direct to the LTM.

Is there any way to tell exactly what is causing the proxy error?