I believe this is a limitation of your formula parser, is there a way to bypass it as this is a valid formula in Excel. The offending portion of the formula is --(X4:X25>0)).
Given the formula :
=+(SUMPRODUCT((X4:X25>0)*X4:X25*$E4:$E25))/SUMPRODUCT($E$4:$E$25,--(X4:X25>0))
I get the error :
Error in Cell: W8-Invalid formula:"=+SUMPRODUCT((W4:W7>0)*W4:W7*$E4:$E7))/SUMPRODUCT($E$4:$E$7,--(X4:X25>0))".
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: Aspose.Cells.CellsException: Error in Cell: W8-Invalid formula:"=+SUMPRODUCT((W4:W7>0)*W4:W7*$E4:$E7))/SUMPRODUCT($E$4:$E$7,--(X4:X25>0))".