Howdy, welcome to the forum! As you might have already figured out, this is a great community full of people who love to help.
If possible, post the macro itself so we can take a look at it and see what might be going wrong. As one of the moderators likes to say, "If we're not testing we're guessing, and guessing often wastes people's valuable time". 
If you need help on how to post the macro, just let us know and we can walk you through it.
If you havenāt had the opportunity to read this tutorial, I highly recommend it. It will help you get the most help for your question.
Tip: How Do I Get The Best Answer in the Shortest Time?
All that being said, are you sure the front window exists when the macro is triggered? Because oftentimes when applications launch (as opposed to activate), it takes several seconds for the front window to exist, which means if your macro is being triggered by the āapplication launchesā trigger, it is likely being triggered too early. You may need some sore of pause until front window exists. You can look at the KM Engine log to see if there are any āaction failedā entries when you run the macro to see what is going on. Also, posting your macro will help us give you better insight into the issue.
-Chris