SUMPRODUCT Not working across separate workbooks #REF issue

I am using SUPRODUCT to summarise some call data. the call data is in workbook one (call info example) and the dashboard is in another workbook (Dashboard example) I have used SUMPRODUCT in this way before instead of COUNTIF and SUMIF across different workbooks but for some reason on this one if I open the workbook 'dashboard example' on it's own all the formulas show REF as the answer, until I open the 'calls info example' workbook - I don't really want to store the data on the same workbook as it will make it too big eventually - this is why I separated the data and the dashboard. I don't want the user to have to open both workbooks either

Like I said, have used SUMPRODUCT to achieve this before with other data (not necessarily calls and time data though) so I am not sure what I am doing wrong?
FYI This part of some of the formulas is because I only wsnt to look at calls greater than or equal to 30 seconds 'Calls info example.xlsx'!Table1[Duration]>=0.000347222222222222

any help appreciated.

Make sure the referenced file is open.