ggplot2正在跳过x轴上的时间间隔

I am using R 3.2.3 through RStudio Version 0.99.491, on Windows 10 64bit...Making my first geom_line ggplot chart I thought I successfully navigagted the problem with the brute force of a newbie. Until, with help, I figured out the POSIXct problem, showing that the graph ticks skip the 02:00 PM interval on the x-axis, going straight to 03:00 PM interval, but with the 02:00 PM data. Here is the I am using R 3.2.3 through RStudio Version 0.99