I’m trying to generate a dodged bar graph that shows the distribution of report ages per report day and overlay the total reports over a critical report age for each day.

When I add the line to the bar graph I get an error:

Error in `geom_line()`:
! Problem while computing aesthetics.
ℹ Error occurred in the 4th layer.
Caused by error:
! object 'ReportAge' not found

Here is my reproducible example:

dt1 <- expand.grid("ReportDate" = seq(ymd("2024-04-25"),
                                      ymd("2024-05-01"),
                                      by = "day"),
                   "ReportAge" = seq(1,7,1)) %>%
  mutate(n = sample(0:10, n(), replace = TRUE)) %>%
  arrange(ReportDate) %>%
  mutate(as.factor(ReportAge))
dt2 <- dt1 %>%
  filter(as.numeric(ReportAge) > 5) %>%
  group_by(ReportDate) %>%
  summarize(OldReports = sum(n))

graph <- dt1 %>% 
  ggplot(aes(x = ReportDate, y = n, fill = ReportAge)) +
  geom_bar(stat = "identity",
           color = "black", 
           position = position_dodge2(width = 0.9, 
                                      preserve = "single")) +
  geom_text(aes(y= -1, label = ReportAge), 
            color = "black", 
            position = position_dodge2(width = 0.9, preserve = "single"),
            size = 3.5) +
  geom_text(aes(label = n),
            color = "red", 
            vjust = -0.3, 
            position = position_dodge2(width = 0.9, preserve = "single")) +
  guides(fill = guide_legend(override.aes = list(size = 0.5))) +
  scale_x_date(date_breaks = "day", date_labels = "%b %d") +
  theme_minimal()

graph2 <- graph +
  geom_line(data = dt2, mapping = aes(x = ReportDate, y = OldReports), color = "red")

In this graph looks fine, but graph2 throws the above error.