enter dates do not overlap when add new period to operand in install. facts

I try to add new period(10/01/2011-10/31/2011) value to exist operand in installation facts, but when I transfer, it said"enter dates that do not overlap". what does that mean?

Edited by: dan421 on Oct 12, 2011 9:46 PM

Edited by: dan421 on Oct 12, 2011 9:47 PM