How exactly did you do the injecting bit? I have dyed by sitting small balls of yarn in a shallow dye bath in the oven - they come out spotty.
I put the balls into equal amounts of water and white vinegar (the vinegar will depend on whether thats your mordant or not) and left it for a couple of hours to make sure that it had got wet right through. Then I used a syringe, like the ones I use for the sheep, just drew up some of the liquid dye and then injected. The end of the syringe only went just below the top surface but obviously the dye must seep through (thats why it has to be wet through) I used dark blue, yellow and red. I then discovered that the red can make it go a bit browny so might add less red next time.
I put them in a plastic bowl filled about half way with the water/vinegar solution and put it in the microwave on medium heat for 10 mins. There was still a lot of colour left in the liquid so put it back in for another 5 mins. There was still colour left but by the time I had let it sit to cool the colour completely went our of the water.
I really should have turned the balls over in the liquid a couple of times during the 'cooking' process as the bit sitting in it got a muddy colour and that on the top looked quite different. Once it was out of the microwave and cooling down I turned it over a few times.
All 3 balls were in together and you can see they look quite different. One ball was very small (just to make up the weight) and the other balls probably had different amounts of the colour added but its all trial and error.
Linda I would love to try a Llanwenog fleece