Rover 75 bonnet problems

[Scoobydodad]

Hi need some advice, just bought a set of bonnet cables and plungers as I call them, all installed work fine when I shut the bonnet and pull the lever bonnet won't open left side is there a certain length the plungers should be I did make the left hand one the same length as the right one still won't open have had to undo the 10mm bolts in the left hand one with bonnet shut to open it, any advice would be helpful.