I am sorry you are experiencing this issue. We will need more details about that in order to come to the root of the issue.
1) Try to change the role of the previous step, that checks if element exists, to "Set as Wait" using the Test Step Context Menu.
2) It may also be useful to set an AjaxTimeout (eg. 1000ms) to the step that selects the dropdown element, if this test step relies on an AJAX.
3) If the previous steps do not help, could you please send us the actual test you're working on, so that we may examine it and propose improvements.
4) Also a short video of the problem might be helpful. Jing is great for this.
Looking forward to hearing from you.
the Telerik team