You would get more replies by giving a couple concrete examples. This is culture dependent, but the feedback that is most well received is the one someone asked

You would get more replies by giving a couple concrete examples. This is culture dependent, but the feedback that is most well received is the one someone asked for. Are you providing a lot of unsolicited feddback on other peoples work? That might come accross wrongly, ask yourself how you would respond if someone told you the same things you are telling them. Trust takes time to build.