Donald Trump Obstructed Justice

Donald Trump obstructed justice.  Period.  Done.  Guilty.  Over.  He broke the law the law and should now be impeached.  

The key line in over 400 pages of the Mueller report is the following:  “The President’s efforts to influence the investigation were mostly unsuccessful, but that is largely because the persons who surrounded the President declined to carry out orders or accede to his requests, . . .” In plain words, he tried to obstruct justice and stop the investigation but didn't succeed because the people who he ordered to do it said "no" because they knew they'd go to jail. '

This Mueller Report line leads to two questions. First, if his attempts to obstruct were "mostly unsuccessful", which ones were successful? What did he do that didn't get stopped and what was its impact? And, by definition, if he did then why shouldn't he be impeached for obstruction of justice? Second, obstruction of Justice doesn't need to be successful in order to be a crime, the mere attempt at obstruction IS THE CRIME. It's like attempted murder, you don't have to kill the person to be guilty. So, by definition, why should Trump not be impeached for obstruction of justice?