I've been trying to run Amelia II in the GUI, but I continue to receive the following error message:

There was an unexpected error in the execution of Amelia. 
Double check all inputs for errors and take note of the error message:

Error in if (any(sapply(x, var, na.rm = T) == 0)) { :
    missing value where TRUE/FALSE needed

What does this mean, and how do I correct this?
 
Thanks,
                 Josh Loud