quick disconnect couplers

I have a 4300Y with a blade, sweeper, scoop and mower deck. I had my blade on all winter to handle heavy snow on our sidewalk route. I put the cutting deck on to mow our grass for the third time. I now want to ut the blade back on to do some leveling in our backyard. I am having trouble getting the quick disconnect couplers to go together. Am I missing something here. I know how they work but it seems as though they won't couple up. Please help me out. Thank you

Ken
Cleveland Ohio

quick disconnect couplers