I'm testing REST results in the browser with mixed results.

The following URL returns the expected result:

`https://xxxxx.sharepoint.com/sites/site/_api/SP.UserProfiles.PeopleManager/GetUserProfilePropertyFor(accountName=@v,propertyName='Manager')?@v=%27i%3A0%23.f%7Cmembership%7Cxxx@xxxxx.com%27`

however the following URL returns an error:

`https://xxxxx-AppGUID.sharepoint.com/sites/site/_api/SP.AppContextSite(@target)/SP.UserProfiles.PeopleManager/GetUserProfilePropertyFor(accountName=@v,propertyName='Manager')?@v=%27i%3A0%23.f%7Cmembership%7Cxxx%40xxxxx.com%27&@target=%27https%3A%2F%2Fxxxxx.sharepoint.com%2Fsites%2Fsite%27`

I get the error code `-1, Microsoft.SharePoint.Client.ResourceNotFoundException` and error message `Cannot find resource for the request sp.userprofiles.peoplemanager.` Google doesn't offer up much for the errors. Fiddler responds with a `404` result. I've tried leaving the URL unencoded, tried with lower case `sp.userprofiles.peoplemanager` and `getuserprofilepropertyfor` with no luck whatsover. I have also tried other methods within sp.userprofiles.peoplemanager. What am I doing wrong?