wt.epm.EPMDocument cannot have more than one type

This is a new installation of 10.2 M030, where creating sub type for EPM Document failed.

But sub type for the Part is successfully created.

Below is the error message :

Caused by: wt.util.WTException: wt.epm.EPMDocument cannot have more than one type.

Nested exception is: (wt.epm.util.EPMResource/132) wt.util.WTException: wt.epm.EPMDocument cannot have more than one type.

    at com.ptc.core.lwc.client.forms.GenericLWCFormProcessor.doOperation(GenericLWCFormProcessor.java:88)

    at com.ptc.core.components.forms.DefaultFormProcessorController.executeDoOperation(DefaultFormProcessorController.java:537)

    at com.ptc.core.components.forms.DefaultFormProcessorController.performExecuteDoOperationAndPostProcess(DefaultFormProcessorController.java:341)

    at com.ptc.core.components.forms.DefaultFormProcessorController.execute(DefaultFormProcessorController.java:262)

    at com.ptc.core.components.forms.FormDispatcher.callControllerExecute(FormDispatcher.java:146)

    at com.ptc.core.components.forms.FormDispatcher.callFormProcessorController(FormDispatcher.java:116)

    at com.ptc.core.components.forms.FormDispatcher.execute(FormDispatcher.java:93)

    ... 51 more

Caused by: (wt.epm.util.EPMResource/132) wt.util.WTException: wt.epm.EPMDocument cannot have more than one type.

    at wt.epm.EPMSoftTypeValidator.checkParentHierarchy(EPMSoftTypeValidator.java:213)

    at wt.epm.EPMSoftTypeValidator.validatePreCreate(EPMSoftTypeValidator.java:102)

    at com.ptc.core.lwc.server.cache.ExternalTypeValidatorHelper.validatePreCreate(ExternalTypeValidatorHelper.java:66)

    at com.ptc.core.lwc.server.cache.TypeDefinitionManager.createTypeDef(TypeDefinitionManager.java:1901)

    at com.ptc.core.lwc.server.StandardTypeDefinitionService.createTypeDef(StandardTypeDefinitionService.java:156)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:606)

    at wt.services.ServiceFactory$ServerInvocationHandler.invoke(ServiceFactory.java:399)

    at com.sun.proxy.$Proxy9.createTypeDef(Unknown Source)

    at com.ptc.core.lwc.client.forms.CreateTypeFormProcessor.createTypeDefinition(CreateTypeFormProcessor.java:327)

    at com.ptc.core.lwc.client.forms.CreateTypeFormProcessor.processForm(CreateTypeFormProcessor.java:94)

    at com.ptc.core.lwc.client.forms.GenericLWCFormProcessor.doOperation(GenericLWCFormProcessor.java:69)

    ... 57 more