In almost all cases a problem like this is down to the f connectors not making proper contact. This can be down to the use of the much thinner WF65 coax, where the centre core that sticks out of the f connector is much thinner than 100 grade coax. Some boxes might make contact others don’t. Try putting a small kink in the core and connect again.
WF65 (usually fitted in a twin (shotgun)) form
http://www.maplin.co.uk/p/webro-wf65-cu-twin-coax-cable-black-priced-per-metre-a53ra
WF100 (usually fitted as single cable)
http://cpc.farnell.com/webro/wf100-black-50m/wf100-coaxial-cable-black-50m/dp/CB14804?CMP=KNC-GUK-CPC-GEN-KWL-WEBRO&mckv=sGukIHzfR_dc|pcrid|190143186916|kword|_intitle%3A-%20webro%20-%23inurl%3Ahttp%3A%2F%2Fcpc.farnell.com|match|b|plid|&gclid=CjwKEAjw_bHHBRD4qbKukMiVgU0SJADr08ZZq5lApbDDckQl6tEg5DL0qZh49AwI0bmM4c7BFwD0RhoCMMbw_wcB