Thanking a professor for their effort Some time ago I had emailed a professor regarding the original data of an experiment they'd conducted almost two decades ago. He replied today to apologize as he had unfortunately not found the data after looking for it for a while.

How can I thank the professor for his efforts without coming off as condescending? Something like "Thank you very much for going to the trouble of finding the data" sounds to me like I still expect something and simply saying "Thank you for your effort" comes off as condescending to me, but this may be because I am not a native English speaker.
It would be fine to simply write

"Dear Professor X,

Thank you for taking the time to look.

Best wishes,

JansthcirlU"