Trying to build a sheet that will total data from 35 sheets

edited 12/09/19 in Smartsheet Basics

I have 35 customer sheets built.    I want to build a sheet that will total everything from these sheets to the Total sheet.

After I get so far I get the error message :

Unable to create a cross sheet reference because this sheet already contains the maximum number of different cross sheet references.

I was only at 15 cross references...meaning 15 cells that summed 35 sheets of a cell.

Is it really this limited?