if null, then formula problem

Hi! It's my first post to this forum and I'm really hoping someone can help me. In my head what I want to do is completely logical...so here it goes...

In my words: I want cell G2 to calculate a date 14 days after the date in D2 only if the cell E2 is null.

What i've tried based on other posts from this forum:

=IF(ISBLANK(E2), (D2+14)) and get FALSE.

=IF(ISBLANK(E2),"", (D2+14)) and get a random number that is nothing close to a date

Any ideas?? Any help is greatly appreciated!