Hi,
Have you followed all these steps:
https://docs.kentico.com/display/K8/Registering+custom+macro+methods
Most likely something went wrong when Registering your new macro. See the "Registering" section on the link above.
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If these are correct where are you trying to call your macro? Is it just your macro that's not working? Try a default macro to see if that works:
{% SiteContext.CurrentSiteName |(identity)GlobalAdministrator%}
You might be trying to call a macro on a place it doesn't work or in the wrong way.
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you could try the Kentico Macro Benchmark / or Console section of your installation to test your macro:
System > Macros > Console/Benchmark
Greets,
David