Using "match" with dates - dates entered with vba return error

Hi there, I hope somebody can help.
I have a function in an excel sheet which matches dates of the year (contained in column A) in the format dd/mm/yyyy with dates of bank holidays and staff holidays (entered in the same format), and uses the result to obtain a second value (the second value relates to whether it is a full day's holiday or a half day's holiday. It looks like this:

INDIRECT("HOLIDAYS!C"&MATCH(A4,HOLIDAYS!$B$1:$B$100,0))

The function works fine when the date of a holiday is entered manually, but when it is entered using a form it does not work and returns "#N/A".

I have tried adding the date as a value; as text then formatting the relevant cells; using format(CDate(DateBox.Value),"dd/mm/yyyy") but none of them work, including when I reformat the relevant cells using Selection.NumberFormat = "dd/mm/yyyy".

I'd be grateful for any advice as to how I might get over this problem without allowing users to have direct access to the relevant worksheet

Thanks in advance

Is

Thanks for the reply Joseph. I'm afraid I've tried this as well but get the same error. I am guessing that one safe way around it would be to record all the dates in the spreadsheet in text format. While the dates currently look identical in the spreadsheet there is clearly a difference between those entered manually and those entered using a form, otherwise 'MATCH' would work fine. Does anyone have any suggestions about doing this.

Thanks

I think I've solved it using the DateValue function. I did check all the dates and they were all formatted as dates so I can't say why CDate was not working.
Thanks for your help Joseph.