That is because of the amount of Steam inventory items which our bot has to process, causing it to get slown down by a lot. You will have to keep waiting until the trade fails or goes through.
Trade Offer
Auto-Sell Hats
Automatically sell up to 100 of your eligible hats at once.
Don't worry: we won't take special items, including painted, low craft numbers, special levels, spells, killstreaks, etc.
Autosell Cards
Automatically sell up to 1,000 of your eligible cards at once.