If you see black screenshots, you can follow these steps to troubleshoot the problem (please note that if you're seeing black screenshots from one of your employees, then it is your employee who will need to follow these steps):
1 - Update your Silah desktop software to the latest version. You can download the latest version at [enter Silah download link here]
2 - Try disabling your antivirus software. Sometimes antivirus software can prevent screenshots from happening. If the screenshots start working again when your antivirus software is disabled, then you'll need to re-enable the antivirus software and adjust the settings in your anti-virus software to allow the screenshots, or contact your antivirus software provider for support with this issue.