Check your tracker clock setup is set UTC-0 o GMT. (The most trackers come from the factory on UTC.)
For most devices you should use IMEI (International Mobile Equipment Identity) number as unique identifier. However, some devices have vendor specific unique identifier, for example TK-103 devices use 11-digit identifier.
Set Up the Plaspy's IP and port on your tracker: (Plaspy detects tracker's protocol.)
Add a Plaspy Account on devices with the IMEI or unique ID.