In order to help you, please, provide us with the following information:
1. Send us an Activity log after the actual connection attempt (click "Show log" -> "Send to technical support" -> enter your email address and leave a few comments).
2. Please check whether there are any SyncMate crashes in the Console.app.
You can find the crash files here: ~ / Library / Logs / DiagnosticReports
If you find them, please send those files to us.
3. Please also send us the screenshot demonstrating the black screen that you've described.