Err:502 When referencing a cell in another sheet

When trying to use the following formula, I am presented with “Err:502” in the cell where I had expected my results.

=SUM(“Average Prediction”!A2)

I am using Collabora Online (v3.4.2) on a Nextcloud 16.0.4 instance, which is running from a Debian 10 Virtual Machine.

For reference, this is the cell I am referencing in the formula:

If you only want to reference one cell, SUM is superfluous. When referencing sheet names containing spaces, use ’ instead of " - the latter will give a 501 error. You also need a period rather than an exclamation mark as the join for sheet and cell, so =$'Average Prediction'.A2 will work to reference the cell; alternatively if you want to sum a range then =SUM($'Average Prediction'.A2:A7) is the correct syntax.

Tested in LO - I don’t have access to Collabora online to see if there are syntax differences

This has worked perfectly, thank you very much for your response to my question.