Under GarageSale > Preferences > Advanced, there is a checkbox called “Log FTP and WebDAV traffic to console”. Please check this box, open the Console application (under /Applications/Utilities/), and scan the output from GarageSale. Maybe that gives you some idea what’s going wrong.
Thank you, Ilja, for this hint. I did this, but the only result I got were these two messages at the program startup:
15.02.15 11:26:07,851 GarageSale[1527]: Error loading /Library/Audio/Plug-Ins/HAL/DVCPROHDAudio.plugin/Contents/MacOS/DVCPROHDAudio: dlopen(/Library/Audio/Plug-Ins/HAL/DVCPROHDAudio.plugin/Contents/MacOS/DVCPROHDAudio, 262): no suitable image found. Did find:
/Library/Audio/Plug-Ins/HAL/DVCPROHDAudio.plugin/Contents/MacOS/DVCPROHDAudio: no matching architecture in universal wrapper
15.02.15 11:26:07,851 GarageSale[1527]: Cannot find function pointer NewPlugIn for factory C5A4CE5B-0BB8-11D8-9D75-0003939615B6 in CFBundle/CFPlugIn 0x7fdf7206f9e0 </Library/Audio/Plug-Ins/HAL/DVCPROHDAudio.plugin> (bundle, not loaded)
Does this is in any way connected to my FTP problem?
Sorry, doesn’t seem like the output is connected to your FTP problem.
The only solution I can think of is to contact our support at garagesale@iwascoding.com and give them temporary access to your FTP account, so we can diagnose the problem.