I bond State of Illinois Deduction

I spoke with the Illinois Dept of Revenue and they confirmed I bond interest is free of state tax.  Unfortunately TT will not allow me to make that adjustment on the State Form.  I have been on the TT help line for over 2 hours and no closure by the TT experts.  Can someone assist?  There is a line on the State of Illinois form to handle government bond interest but it is not possible to enter a value.

 

Thanks!