Smart FTP won't start

By installing Smart FTP I made a mistake, I think. What happened?

I installed Smart FTP and wanted to place my favourites (backup) back. I opened the ZIP-file and clicked on the register-file. My favourites and history were not imported at the right way, so I tried to run the backup tool. That leads to errors. So, I uninstalled Smart FTP and resinstalled it. Nothing happened: I could not open SmartFTP anymore. I read some forums and saw that I had to clean register from SmartFTP values, I get the latest version, but I can't get it working anymore. What do I have to do????

1. Open regedit.exe
2. Go to the HKEY_CURRENT_USER\Software\SmartFTP\Client 2.0 key/folder
3. Delete this folder

1. Open regedit.exe
2. Go to the HKEY_CURRENT_USER\Software\SmartFTP\Client 2.0 key/folder
3. Delete this folder

I had done that already. Doesn't help.