Changing the fill colour of cells, based on other cell inputs. #VALUE! error.

Hi.

I have a calendar set up with dates going along P6:CU6. Column C9:C27 has various status' for the job such as "Complete" or "In Progress" etc. Next to that in rows D and E I have start and end dates for the job. What I am trying to do is change the fill colour of the empty cells that are in line with each job, so that between the correct dates they are the corresponding colour to the status. So a complete job on row 9 that started on 26/05/14 and finished on 28/05/14 would have three green cells along Q9, R9, and S9.

I have tried an IF/AND/OR statement which looks like this:

=IF(AND(Q6>=D9,Q6<=E9),OR(IF(C9="Planned","P",""),IF(C9="In Progress","IP",""),IF(C9="Late","L",""),IF(C9="Complete","C","")),"")

I am getting a #VALUE! data type error, I have tried reformatting the cells to various date formats but no luck so far. This could be because my dates are set up as =P6+1 etc. but I am not sure. The error only occurs when the cell falls within the dates, otherwise it remains blank.

I intend to hide the value in the cell and use conditional formatting to change the cell colour based on the hidden input.

Once this is working I also need to take weekends into account, column G has any 2 value combination of Y and N to say whether the employee is working Saturday, Sunday or both (poor guy). Row 7 has a "1" value underneath every Saturday and a "2" underneath every Sunday. I can imagine how this would work but combining it with the above formula could be complicated.

I am fairly new to excel as you can probably tell so any tips, pointers or suggestions would be appreciated. Let me know if I haven't given enough information to solve.
Thanks.