viburnums

I have one viburnum tinus Eve Price, 2 viburnumn bodnantense dawn and one viburnum tinus.  None of them are flowering.  The bodnantense ones have been in for 3 years and I've had no flowers at all.  They all leaf up very well.  I've tried putting sulphate of potash on them.  I was told chicken manure would help them so I've also tried that but I'm still getting nothing.  It's very disheartening. What am I doing wrong?

Have they been pruned at all?

need to cut them right down to ground level then watch it grow and verburnum flowers twice once in spring and winter a had one but it was a nightmare getting it out as the roots go deep

Not so sure about pruning a Viburnum that hard. Never had to do it to any of ours and we have , at the last count, 28 different ones.