ZBrushCentral

Problem with old ZTL files

Well I tried posting this in the Troubleshooting forum but no one replied. So I decided to post it here:

Does anyone know why I can’t open ztools that were created way back in 2004 or 2006? Instead of being a head or something recognizable, it just looks like a big box. The same thing happens even when I go back and try opening it in all the previous version all the way back to 3.12. BTW: I am running ZBrush on a Mac running Mountain Lion (10.8.3).