For some Strange Reason can no longer drag and drop uploads

I have been using SmartFTP all day to day, dragging and dropping files up to my server, no problems. Basicall have two windows open local computer of files I want to upload and then a window for my active connection to my server to where I want the fiels to go, then "drag and drop".

THen when I closed SFTP to go take a break and came back opened SFTP I tried to drag and drop mores files it will NOT let me. THe only way to get files up to my server is to click on the connection window to my server, right click then select <Upload><Direct><Select Files>

This is a very slow way to upload files can someone tell me what casued SFTP to do this, did I make some setting change and not even know it?

Thanks in advance for any and ALL help!