Issue: Sell listing keeps asking to add after selecting "Trade Only"

[Ludacus]

I feel like I'm just being an idiot but I keep trying to create a sell listing for my Australlium Rocket Launcher but even though I make sure to tick the box stating I'd rather not be added, when I create the listing it says add instead. I've made sure my Inventory Privacy is set to Public. Am I doing something wrong?

[Beaser]

you have not linked your trade offer url in the settings https://backpack.tf/settings

[Ludacus]

God damn it, Thank you.