Daniel,
Which did you install first, IMAQ or LabVIEW? If you installed the IMAQ software first or if you did not specify to install support for LabVIEW 6.1, then the VIs would not have been installed for your system. Try going into Add/Remove Programs from your Windows Control Panel and then choose to modify the installation of "NI Software." Then select the IMAQ 2.5.2 drivers and choose to change that installation. Navigate through the custom installation screens until you come to a point where it asks you what software support you want to install. Be sure that LabVIEW 6.1 has been selected and that support has been installed on the local drive. If the problem persists, try uninstalling and reinstalling the IMAQ drivers and be sure to install LabVIEW support.
Try those steps and let me know if you have any additional questions on this issue.
Regards,
Scott R.
Applications Engineer
National Instruments
Scott Romine
Course Development Engineer
National Instruments