Deductions & credits

I do income tax for my grandson who is employed by a contractor in Afghanistan.  I use Form 2555 for Foreign Earned Income exclusion.  I have efiled this for about 5 years on Turbo Tax.  This year it was rejected saying that a tax return with Form 2555 had to be mailed in.  I have a POA to sign for him but was wondering if it will be rejected again because he hasn't signed it himself.  And why would it be rejected just this year?