Linking to specific powerpoint slide

I have a table in excel where i'm trying to hyperlink to specific side in a powerpoint presentation. I've found various sites instructing me to use #slidenumber (eg #4) at the end of the filename when editing the link, however many different combinations of slide numbers and names i use it refuses to open the deck at that set slide, always taking me to the begining. I've tried using the bookmark option in excel but that gives a error messagaing stating bookmarks cannot be used in xml files.

Come to a bit of dead-end on this, anyone have any ideas on how to get around this issue?

Thanks

I have found, that for this to work, the file must be saved as .PPS or .PPSX