To use the eSign Signature Capture plug-in within a Terminal Server environment, you’ll need to configure your Remove Desktop Connection to allow Local devices and resources. Please follow these steps:

1) Open the Remote Desktop Connection application
2) Under the Local Resources tab, select the “More...” button under Local devices and resources
3) Enable the “Other supported Plug and Play (PnP) devices option

Also, you will need to follow the instructions from Topaz for using the signature pad within a Terminal Server environment. See this link for details:
http://www.topazsystems.com/remoteusage.html