Why does your script of code manipulate Data1 and then report some facts about an df before attempting to plot with Data1 ; is df at all relevant ? Not sure if its a case of you not cleaning up your code; or if its a sign of confusion about how your code works. On its face your error seems impossible as its a claim that Data1$Date is both zero length and length 34433; I struggle to see how I could make my R session believe this about any variable of mine... the closest I can get is if I clearly mistype the variable on the right , so the non-existant column is zero length; but yours doesnt appear to be mistyped.
Its hard to fix any bug that can not be reproduced, to read about reproducing bugs; please read: