This behavior is generally caused by an element of the project, such as a dependent VI or library, being locked or uneditable. In order to track down what file is causing this problem:
- Go through the files stored in your project and check to see if any of them are locked. This can be done by opening the Properties dialog box and checking the "Protection" section to see the lock status of the file.
- If the option is there, try to save the project using the Save for Previous Version option and select the same version of LabVIEW as the one you're currently using when saving the project for a previous version. You should be able to save the resulting project files using the Save As... function.
- If none of your files are locked and you're still unable to use the Save As... function, you should manually remove files from your project to see what files are preventing the Save As... function from being used. After removing each file, check to see if the Save As... function is enabled - once it is, start adding VIs back to determine which VIs are preventing the project from being saved using Save As...