Rest API - Update database performance tier problem

Hi,

I am attempting to change the database performance tier using the REST API but it does not seem to do anything. The result of the request is an OK response and checking the database status via the REST API shows that no errors have occurred and that the ALTER DATABASE command has completed but the performance tier has not changed.

I can successfully change the database name via the REST API.

I have also not reached the limit of 4 database changes in a 24hr period.

Here is an example of the XML body in the PUT request

<ServiceResource xmlns="links not allowed" xmlns:i="links not allowed">
 <Name>TestDatabase</Name>
 <Edition>Standard</Edition>
 <ServiceObjectiveID>f1173c43-91bd-4aaa-973c-54e79e15235b</ServiceObjectiveID>
</ServiceResource>

Does anybody have any pointers as to where I am going wrong?

Cheers