Box 7 on 1099-R is blank. Turbo will not allow me to move on until I put something in Box 7. What do I put in box 7

I bet the code is a "7".  That's the most common.  And it is the same as the box  # so you  might miss it.    Otherwise ask the issuer for a corrected 1099R.  

If you received a Form 1099-R with no distribution code in box 7 of the form, you need to contact the Payer to get a corrected 1099-R.

VolvoGirl indicated, it's common for people to fail to see the code present in box 7 when it happens to be the same numeral as the box number.