open door so you can see lockstrips bolts/hooks then pull handle up then turn key,if its ok then your door will need repacking or your door keeps need adjusting(take one off at a time then try each time and yo might be able to sort it that way)if it dosnt lit sounds like lockstrip has failed and you will need a new one,and I would get it repaired asap because fullex handles break verry easily and they are expensive to replace so try not to force them to much
shaun www.sdwupvcrepair.co.uk, July 2008
