Conditional formatting on dates if another cell equals to

Hi,

I'm currently making a production planning sheet, and i have just reached a point where i'm facing some problems.

I have attached a picture of the sheet, so that my explanation of my problem is easier to understand.

My sheet books time in the calender for each production order based on dates, that works fine. Now i want to assign different production cells to each production order, and if i for instance type cell1 one in one of the cells under "PO assigned to cel", then i want to make the sheet automatically color the booked dates in calender with a given color. so far i have only been able to color the whole row red, i want it to only color the booked dates in the calendar.

If anybody could help on this matter, i would be very happy.