DatePicker Question

I wish to insert a DatePicker into my spreadsheet to allow users to select dates from the Calendar rather than inputting dates manually, which I have managed to do and it looks to perform as expected.

However I also want to link the DatePicker to a cell that is used in subsequent formulae in the workbook. I have managed to make this link (via the Developer > Properties > Linked Cell function) and it appears to put the selected date in the cell, BUT the formulae appear to read this date as a text input and not as a date, hence I'm getting #NA errors. Reading up on this the linked cell the linked cell should recognize the date as a "date" and perform as such in the formulae - am I missing something?

Thanks in advance

See if this video helps you to use a add in datepicker
https://www.youtube.com/watch?v=5pdcLTwkn5s

I have attached a reply I gave to another query some time back.
See if any of it is a useful guide to what you are doing.
The datepicker is on a form and appears as you click in any cell in column A.
This cell becomes the target for the date and all calcs and data are then related to that row.
The combo box is a further addition to answer a follow up question from another query.
The sheet scrolls to keep the inputting in related position to the datepicker.
The form can be closed and the sheet scrolled to view.
Happy coding.
torachan.