Using VBA Find smallest date larger than refdate for each lotid

I have two columns of data (see enclosed file).

What i want to do is find the smallest date larger than the refdate (in cell E1) for each lotid. If there is no date larger than the refdate for a given lotid then return "n/a".

So ideally, i would have two output columns (see file.....cols H and I) where in col H i have the lotid and in col I have the smallest date larger than the refdate.

I want to do this via VBA.

Any ideas?