Problems loading dls file

[vnacooper]

I have a plugin physio.dls to collect physio data, which works fine on two different machines running Vizard 2.5. However, the file fails to load on a third machine running the same version of Vizard. I have tried placing copies of the physio.dls file in the same directory as the script, as well as the plug-in directory in the Vizard install folder. Any ideas what could be going wrong? Thanks!