"Error validating device name" means that the device is unable to connect to the Wasp MobileAsset Windows Service, which is the component the validates the device name.
This is a connectivity problem, not a problem with the device name. Troubleshoot the network connection between the device and the Service PC.
MobileAsset v7: mobile device connection troubleshooting:
HC1 & WPA1000-II: Network configuration to enable name resolution and/or internet browsing:
WDT60: Network configuration to enable name resolution and/or internet browsing:
Windows Mobile Device Center settings interfere with mobile device's connection to Wasp service:
Summit Client Utility: How to set up wireless, and choose from multiple SSIDs (wireless networks):