The RemoveADComputer function in child domain (parent domain works fine) does not work. The permissions in Active Directory is not the problem. When trying the function on http://server/ConfigMgrWebService/ConfigMgr.asmx, the following error is displayed:
System.NullReferenceException: Object reference not set to an instance of an object.
at ConfigMgrWebService.ConfigMgrWebService.RemoveADComputer(String secret, String samAccountName)
The GetADComputer function is working without problems in the child domain. Setting the Description with SetADComputerDescription is working as well.