Hi, don't know if this is still outstanding or not....
We can help with the truck, but not necessarily the charger. The obvious thing to check after connecting the charger is if it it actually charging the battery. To do so check either the Specific Gravity reading or voltages. Depending on the model and age of the truck the correct battery voltage may also need to be programmed into the truck to get the display panel and control system showing the correct state of battery charge. If you let me know the Model and Serial number of the Thesi truck we can possibly help.