On NNM you should find 2 lof files: sd_event.log --> showing what NNM is trying to send sd_event_error.log --> showing why something has not been sent from NNM to OVSD.
If something is not sent from NNM to OVSD you might also see it on NNM from the file ovactiond.log
On OVSD, you can check what comes from NNM from this log file: "C:\Program Files\Hewlett-Packard\OpenView\service desk 4.5\server\log\logserver.txt"
Having this said. From OVSD side, did you activate the HTTP protocol? You can check by clicking: Start-->Programs-->hp OpenView service desk 4.5-->application server-->openthe server settings editor-->HTTP
Also, you might want to install a sniffer on OVSD to see if NNM is sending somthing or not to OVSD.