Reporting RMD on inherited Roth IRA

I am going through smart check on Turbotax, having entered in all my tax information.  I get a screen that is saying "Check This Entry.  Form 1099-R (CHARLES SCHWAB & CO,INC): RMD amount should have an amount since this IRA is inherited.  If there was no RMD for this account, enter 0 for the amount."  

 

First, I received three separate 1099-Rs from Charles Schwab so I am unsure which 1099-R it is referring to, but perhaps I can assume that it is one or both the the 1099-R forms for the two Roth IRA accounts I inherited from my mother in 2012.  I did receive an RMD from each of those accounts this past year.  But when I enter the amount of both of the RMDs (approximately $5,400) , my tax bill goes up by $1,363.  I thought that there was no tax on inherited Roth IRAs ?    Why am I getting such a huge tax liability?  Is it a problem with Turbotax?