Help needed to link graph and months together

Hi excel users,

I need some help with a excel file. The problem that i encounter is that i have a graph that will need to trace the last ten days of "slides pending for grading". This graph will help to trace by inputing the dates. However, my current work can only trace to a limited dates(different months not link) and input of dates have to be in different slot for different month. Another thing i would like to fix is that my dates are set to 0.5 days 1 days 1.5days according to day and night. What function should i use so that my vlookup formula in n5 to n26 can trace. i try puting like for example (7.5 (day),8(night)) to (8(day),8(night), however the reading will only look up for the first 8 value that it encounter.
Problem 1 : Error when input is less than 10 at "chart graph" D2, if can i would like to link the different months together in one chart.
Problem 2 : Different slot input for different month
Problem 3 : Date format 7.5 day 8 night confusing, if possible can change it to 8 day 8 night without any problem when vlookup formula is being used.

Hope you can help me! thanks alot (: