Cannot use value of linked cell in xlookup function

Hi
I have one spreadsheet (A) which takes the eight lowest numbers from a list of twenty and then they are averaged. This average figure changes three times a week
I want to put the result into another spreadsheet (B) which uses xlookup to use the average to produce another figure
If I link the cell in spreadsheet A to the cell in spreadsheet B the cell in Spreadsheet B displays the figure, but the xlookup shows N/A, with a warning “A value is not available to the formula or function” The cell doesn’t have the result, it has the formula for the kink
Is there a way to get the figure from spreadsheet A into spreadsheet B as a value that reflects the figure in spreadsheet A
 
Cheers