Error with Line Graph: Broken line graph on R Studio

Hello,

I'm having trouble with producing a line graph between two variables. No matter how many times I try, the line graph for one of the variables is always broken. I did research and saw RStudio official page saying that it coule be solved by changing the size of the panes, but I tried that and it still comes out as the same graph. Can anyone please help me with this? I have this assignment due in one day so please let me know how to solve this if you know? Attached is a screenshot of the line graph and codes.)

Thank you.

Description of issue -

System Information:

  • RStudio Edition: (Desktop or Server)
  • RStudio Version:
  • OS Version:
  • R Version:
  • sessionInfo():

Referred here from support.rstudio.com

Check to see if you have NAs in any of the data.

I have an NA in another question but it's not the same related question with the one I'm having issue with right now.