Milk bar teats faulty

[Suka]

Just replaced two teats on my milk bar and noticed two calves getting agitated. Kept squeazing the teats but neither of them works, absolutely nothing comes out (only bought them yesterday). Will always check them before filling with milk in the future! Is it too much to ask that these things work properly without having to check them?

 

[Suka]

Update: I contacted the supplier, Dairy Spares, who replied really promptly and said occasionally the rubber is too hard to form a good teat and they've offered to replace them. Very impressed with their customer service!