There is no value in Box 9a of the 1099-R form what must I do to continue filling out the Tirbo tax form?

To remove the program error you will have to delete the Form 1099-R and then re-enter the 1099-R manually.

When you reenter it remember to leave boxes 9A and 9B completely blank. Don't even enter a zero as a placeholder.

Generally this is required only when the distribution is split between people.

Per IRS: If this is a total distribution and it is made to more than one person, enter the percentage received by the person whose name appears on Form 1099-R. You need not complete this box for any IRA distributions or for a direct rollover.

Try to delete form 1099-R and enter it again. 

How do I delete a 1099-R?

Where do I enter my 1099-R?

An easier, less painful approach is to click on "Forms", go the the offending 1099-R, click on box 9a and delete anything that is in that field, e.g. "0.0%" needs to be deleted. Run "Smart Check" again.

If you are in the middle of "Smart Check" and it is asking you to enter an amount, clicking on "Forms" will take you directly to the 1099-R box 9a. Just delete whatever is there and go back to TurboTax interview (just click on "Easy Step") and run "Smart Check" again.