If using LabVIEW 6.0x or earlier with Matlab 6.1 or 6.5, download the updated ActiveX ID attached in the above KB.
LabVIEW uses ActiveX to communicate with the Matlab script server and this ActiveX component is not registered until Matlab is opened. Therefore, try opening up Matlab on the computer before trying to use any Matlab component in LabVIEW.
If the Matlab Web Server in Matlab 6.5 is installed, uninstall this feature.
Hope this helps!
Kileen C. Applications Engineer National Instruments