Another note on this... FindChild will find the FIRST child that matches your search criteria... you're searching a tree depth of 10 which means that it is possible that there is an object at layer 3 or 5 or 7 or whatever that matches what you are looking for and that object, when you go to click on it, may be getting destroyed. So, one thing you can try is to verify that 10 is the EXACT depth to find your object so the depth of your search is optimized. Then, before your FindChild call, call the following line of code:
Options.Run.ObjectSearchStrategy = searchDepthFirst;
By default, for new installations and new projects, TestComplete does the FindChild search on breadth-first... it searches each level before it goes one level deeper. So, FindChild will find something on a lower level rather than dive deep first.
Beyond that... You might need to get more specific with your FindChild parameters... are there other properties that will more uniquely find the item you are looking for? Something that will guarentee you'll get the correct item and not some other similar item in the object tree?
Just some things to try...