I have a suspicion you are trying to drag the files from the LimeWire (LW) window to Toast. You can't do that with mac LW to Toast. Below is a sample image animation gif of adding files to Toast. Just drag & drop onto the main window.
To access your LW downld files to you can add to Toast: For fast & easy access, go to your LW Library window, select Saved Files folder & press the Explore button. Sample image here:
Using Library Explore button to access downld folder (click on link) & the folder will open up for you.