how to call Admin Api for rest api?

hi,I am a powerbi administrator and I try to call admin api and Found I can't get data using the aad token I get via the Oauth.

After calling the admin api "https://docs.microsoft.com/en-us/rest/api/power-bi/admin/groups_getgroupsasadmin",I  only get the String "",and nothing returns.

And I click the "try it" button at the page “https://docs.microsoft.com/en-us/rest/api/power-bi/admin/groups_getgroupsasadmin” “

”

and I can get the data. And I open the network tool and found it's using the pbi_access_token not the access_token And I copy the pbi_access_token to my code and it's ok.

so How Can I call the admin api？

But the same token can be used to call other api.

So I don't know where I do the mistake.