washing machine connection leak

[ablebakerout]

Hi, I have plumbed our washing machine in, draining to the spigot under the sink, and have 2 leaks in the drain hose connections. The leaks are a) where the old hose has been connected to a new hose to lengthen it (using a standard connection and jubilee clips each side), and b) from the non-return valve. I was advised not to use jubilee clips either side of the non-return valve as the ends of the valve are stepped and apparently jubilee clips won't secure the hose ends any further. It took a lot of effort to get the hose ends onto the valve as the fit is so tight, but the connections still leak. The valve itself is also leaking from its middle join - it is brand new. The leaks are lessening with time but still definitely there. Does anyone have any idea what could be wrong, and what I could do about it?