If this issue occurs with the add-in installed with different versions of Excel, please also check RealTimeData server or some component files. As this action may focus on Office development, I would suggest you post realted thread on following forum.
Office developer community
From the perspective of the Excel client, you may try the following suggestions.
- According to this link "Security", in addition to enabled macros and VBA projects, please go to Trust Center again, click Trust Center Settings > Add-ins, make sure you do not tick any one of 3 options.
- Please make sure you have the administrator rights to the install your Add-in.
- If you are using 64-bit of Office, you may try to install 32-bit Office to check this issue.
- And you could update Office to the latest version.
Here is a similar thread, you may have a look "RTD #N/A error in Excel", Dana D_ resolved this issue via a clean install of Windows 10.
Hope the information could be helpful.
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