If you aren't able to get labels to output after processing a shipment or from the reprint label button, there are some steps we can take to troubleshoot this.
First make sure you are linked in the top portion of the Shipstore web application. If you see NOT Linked the web software can't talk to the background application. Doublecheck the Merchant app is running in the background. In the lower right of your screen select the ^ symbol to the left of your system clock. Look for the Shipstore logo in your system tray.
Linked
Not Linked
If the Merchant app is running close it from the system tray by right clicking it and selecting exit. Reopen the app and re-login. Make sure the notification you see after login matches the station you are utilizing in the Shipstore web application if these don't match the app can't talk to the web software.
Double check the station currently linked to the Shipstore web software. This shouldn't be NOT LINKED, and it should match the station in your notification when you login to the Merchant app. If your station is not linked the web software can't talk to your printer.
In the control panel select Devices and Printers, right click the printer you are utilizing for your labels then Printer Properties and select Print a Test Page in the bottom right. If this fails, then there is an issue with Windows talking to the printer itself, seek guidance from an IT professional.