Can't tell much from your pics . Are the mating surfaces of the isolation valve and the hose clean and flat ? If so ,are you tightening up sufficiently when fitting the hose onto the valve ?
Yes clean and flat. Trying to tighten sufficiently without over tightening. The problem is you’ve got to do some jiggery pokery to connect due to angle of isolator/supply.
Another picture. Looks fine to me. Have noticed that the old washer sits more snugly in the hose. Ie the lugs secure under the ridges on the hose etc. The new one just falls out easily.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local