org.mockito.exceptions.misusing.NotAMockException on InjectMocks object

I'm trying to mock the return value from a method but I'm getting NotAMockException.

@InjectMocks
private MyService myService;
@Mock
private OtherServiceUsedInMyServiceAsAutowired otherServiceUsedInMyServiceAsAutowired;

Inside MyService I have a method called myMethod() and I want to return dummy object when this method is called.

doReturn(someDummyObject).when(myService).myMethod(any(), any(), any());

And at that point I'm getting the error. What am I doing wrong? Full error:

org.mockito.exceptions.misusing.NotAMockException: 
Argument passed to when() is not a mock!
Example of correct stubbing:
    doThrow(new RuntimeException()).when(mock).someMethod();