Speedo won't work?

hi all, new to the site but not to bikes.

I have a 75 z1-b 900 and I put new gauges and cables on it. The tach works fine but the speedo is a no go......dumb question but on the cable, does the square end go into the speedo and the round end with the slot go into the assembly????? That is the way I did it but the damn thing won't work. Is there a cog or gear in the speedo that might be broke?????? Or do I have the cable backasswards.

what end goes to the gauge? 1 or 2

Square end into speedo is correct. Take a hand drill and turn it on reverse and unscrew your cable at the wheel and connect the end of the cable to the drill and run it and then see if the speedo works. If it does PM me and I have the parts you need to fix it.
Tom