Issue Details

I'm trying to use one of the LabVIEW debugging tools (Highlight Execution, Probe, Step Into, Step Over) but they do not seem to be working in my VI, or are missing/greyed out. What are some potential causes of this behavior?

Solution

If your debugging buttons are not visible, or if you cannot use the probe tool, the likely cause is that one of the VI Properties prohibits debugging. Here are the most common reasons that the debugging buttons are not visible:
 

1. Debugging is turned off in the VI. You can adjust this setting from File»VI Properties»Execution»Allow Debugging.
2. The VI is marked as being inlined into calling VIs. Inlined VIs are incorporated into their calling VIs directly, which reduces execution overhead but also prevents those VIs from being debugged using LabVIEW debugging tools. LabVIEW will not allow you to have a VI configured as inline and debuggable simultaneously. You can adjust this setting at File»VI Properties»Execution»Inline SubVI into Calling VI.
3. The VI is marked as subroutine priority. VIs may not be debugged while they are marked as subroutine priority. You can change the priority classification for the VI at File»VI Properties»Execution»Priority.

Additional Information

If you are using the LabVIEW Real-Time module and your VI is set as reentrant, debugging tools will not be available, along with other LabVIEW features.
If you are using the LabVIEW FPGA module, the debugging tools available will depend on the execution mode and the target selected. Please refer to the LabVIEW FPGA Module debugging documentation for more information.