Relay Server with a Http 500 error (SUP 2.2)

Question

Hello experts,
The history is the following, after upgrading my unwired server from SUP 2.2 SP 02 to SP 05 the aplication stopped working.
We could get Register, but we could but not synchronize.
We connected the device directly to SUP and it worked we could register and synchronize but. when connected to Relay Server only register is possible.
at the moment our only hint is the Http Error 500 that is appearing in the relayserver log. What could be causing the internar error?.
Thanks in advance.
Below there is an example of a Successfull Comunication and a Unsucessful one.
thanks
Laguerta
SUCCESSFUL COMUNICATION
New request for new session from UltraLite/12.0.1.3817 accessing /ias_relay_server/client/rs_client.dll/FARM/ml/APPID/APPVersion
Relaying headers
<Original request header> Content-Length: 1120
<Original request header> Content-Type: application/octet-stream
<Original request header> Host: <-Host IP>
<Original request header> User-Agent: UltraLite/12.0.1.3817
<Original request header> ml-client-id: 3fdf25b0-5efb-11d7-8000-c66fe18554e7
<Original request header> ml-session-id-from-client: 22d75af0-9830-11d7-8000-c7117799da56
<Original request header> X_SUP_APPCID: 150006F0063006B0065007400500043000000434937302D3638323133353231303900__SGFMobility
Start relaying Content-Length body of 1120 bytes
Waiting for response packet
Up padding.
1460 bytes RS_UPCHANNEL_NOOP()
Waiting for client request
Down packet offset 000b8028
527 bytes OE_SERVER_RESPONSE(<F8B0S798R0>;oidx=0;sidx=43;sfp=404d89f3;payload=505;filler=0)
Waiting for server response with trip left: 78987387301
Down packet offset 000b8250
Got next packet after offloading and flow-control. SQ-length=0(ok);LQ-bytes=0(ok);shm=8624608;sfp=404f3
1460 bytes OE_DNCHANNEL_NOOP()
Received down packet
Waiting for server response with trip left: 78987387301
<Response status> HTTP/1.1 200 OK
UNSUCCESSFUL COMUNICATION
New request for new session from UltraLite/12.0.1.3817 accessing /ias_relay_server/client/rs_client.dll/FARM/ml/APPID/APPVersion
Relaying headers
<Original request header> Content-Length: 1616
<Original request header> Content-Type: application/octet-stream
<Original request header> Host: <Host IP>
<Original request header> User-Agent: UltraLite/12.0.1.3817
<Original request header> ml-client-id: 3c9625750-180a-11e4-8000-89c67gh30ec16
<Original request header> ml-session-id-from-client: 0ea17930-1e39-11e4-8000-b0e177c16c6d
<Original request header> X_SUP_APPCID: 150006F006306B006500700500043000000434E37302D3439323133343234393000__APPID
Start relaying Content-Length body of 1616 bytes
Got next packet after offloading and flow-control. SQ-length=0(ok);LQ-bytes=0(ok);shm=8624833092;sfp=6b308e60
Up padding.
Received down packet
1460 bytes RS_UPCHANNEL_NOOP()
Expiring RS session cookie due to previous failure
Waiting for client request
<Response status> HTTP/1.1 500 Internal Server Error

Answer 1

I'm able to Register but not to Synchronize.
what could lead to this situation?
Thanks in Advance
Sync Profile
APPDB.GetSynchronizationProfile().ServerName = <Relay Server IP DEV>
APPDB.GetSynchronizationProfile().PortNumber = 80;
APPDB.GetSynchronizationProfile().NetworkProtocol = "http";
APPDB.GetSynchronizationProfile().DomainName = "DevDomain";
NetworkStreamParams streamParam = APPDB.GetSynchronizationProfile().StreamParams;
streamParam.Url_Suffix = "/cli/iarelayserver/DevRBSFarm"; //Sync DEV
ConnectionProperties connProps = app.ConnectionProperties;  
LoginCredentials loginCredentials = new LoginCredentials(idUser, pass);
connProps.LoginCredentials = loginCredentials;
connProps.ServerName = <Relay Server IP DEV>
connProps.PortNumber = 80;
connProps.FarmId = "DevMBSFarm";  //Login  DEV               
connProps.UrlSuffix = "/cli/iarelayserver/";
connProps.NetworkProtocol = "http";