Forum Discussion
Issue _xlfn.Single and @ being added to formulas - unsupported functions - NOT THE REASON
Katherine, yes, so called implicit intersection '@' was introduced with dynamic arrays in previous year. All details are here Implicit intersection operator: @
Usually it works correctly and could be ignored. An error you have most probably since you used mixed operator like =SingleSource + something. Such errors are also described in above article.
The only way is to re-write such expression differently.
I have come across this issue a few times over the last few months, and after a quiet spell it re-occurred today. I sent a workbook to a client who is on exactly the same version of excel as me (2011 13426.20332). 3 index formula that I had written (without the implicit intersection '@'), had been automatically changed by excel so that they now had the @ symbol. When I sent the file to my client, on opeing the file that @ symbol had changed to _xlfn.single and so was now returning the #NAME? error.
To fix the issue, I must go back into my copy, delete the @ symbol, and save&send again.
This surely must be a bug in Excel, under the circumstances.