Recently wired a ceiling rose in a new house. Did the hall downstairs fitting LED lamps and they are OK but the ones upstairs on the landing are proper screwed up.When I switch on the new light upstairs the other lights in the 3 bedrooms will not light up until the landing lights are off. The bathroom light upstairs are working fine and are not affected by switching on or off of the landing lights.I have checked all the connections and can see no obvious error. What I really should have done before removing the old ceiling rose was to make note of all the connections but I had just done the downstairs one and was confident it would be the same upstairs. I have only done the ceiling rose and none of the switches. Any ideas of what I need to try. Thanks.