Win98/dos Stacker 4 False Out Of Disk Space Issue

Hi! I have a Win98 computer at my mother's house. I also have a DOS laptop with no hard drive. I've been using two Zip100 disks, two RAM drives and a network with the Win98 computer to act as hard drives. The network requires the Win98 computer to be in DOS mode. I compressed the Zip100 disk connected to the Win98 using Stacker 4. Now, the drive keeps giving me an Out of Disk Space error, even though a DIR listing reveals plenty of free disk space. What could cause this, and how do I fix this?