This issue may occur by different possible causes which are covered in the following article with their respective troubleshooting steps.
If the NI VLM version is incompatible, upgrade it to a newer VLM version. If your software administrator is running the FlexLM/FlexNet Publisher, they will need to upgrade the vendor to a newer FlexNET daemon version.
If you are using concurrent unmanaged Licenses, the activation status under Network Licenses remains default grey even If you have access to them. This is a purely cosmetic issue and should not prohibit your access to the software. For more information, refer to Unable to Activate Software Using Concurrent Unmanaged Network Licenses
In some rare cases, there may be a problem with the options file.If you are a software administrator please try to copy across the nilm.opt file on the license server from C:\ProgramData\National Instruments\Volume License Manager to the location of your original license file (where it was originally imported from) then restart NI License Manager on the client.
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