In order to run your CVI application in an external compiler, you will need to create a UI callbacks table and add it to your VC project. To do this, run Build>>External Compiler Support and follow the instructions there.
If you've already done this, then make sure that the file is up to date with the latest callbacks that you've added to the UI. (You should probably tell CVI to create it as a source file, instead of an object file, so that you can easily look at it).
Finally, if you are already doing this, and you know the file is up to date, make sure that you are calling InitCVIRTE before you call LoadPanel.
Hope this helps.
Luis
NI