Don't know how to automatically pick scale for object of type data.frame defaulting to continuous ggplot R

I guess its pretty simple but a tricky error and not able to solve while following Question.1, Question.2 on stack overflow and some other forums. Most of the discussion says that either my column name is not mentioned or the name of column is the same as function name in R. I don't have both cases. Mentioned below is my dataframe Diff_Pat and code to plot it is below

    Year    Pat_Val1    Pat_Val2
1   2007    224564      20145
2   2008    214578      45128
3   2009    12124       20124
4   2010    48547       20124
5   2011    21248       20121
6   2012    131168      90078
7   2013    126485      87966
8   2014    126989      88524
9   2015    122828      86298
10  2016    124182      86922
11  2017    124858      86923


abc=ggplot(Diff_Pat , aes(x=Year))+
          geom_line(aes(y=Pat_Val1),colour="red")+
          geom_line(aes(y=Pat_Val2),colour="green")

When I run the code to plot a geometrical line, it says

Don't know how to automatically pick scale
for object of type data.frame. Defaulting to
continuous. 

I don't know how to solve this error or should I plot it in a different way ?

Thanks