Problem with simple "move file" rule

I'm a new Hazel user and I'm having a lot of problems. I'm getting frustrated and am ready to give up! I created a simple rule to watch a folder and when a pdf file that contains specified words is put in the folder, the file is moved to another specified folder. Hazel tries but does not complete the move. The log says "Error moving file" and "-47 - File is busy (delete)". If I duplicate the file and create a copy, both files are immediately moved. Does anybody know what's going on?