From what I see on my screen you have yellow & purple - complimentary colours should work; and red & green - also complimentary colours, also should work. However the green is a greyish olive green and I think that that is pulling the colours to their greyer shades and making the combinations 'sad'. Also it is reading as medium light through to medium dark in value - could that be part of the problem?
How to fix it, I really don't know, would adding clean pure colours work? or adding in the last 2 complimentary colours (blue & orange)- not sure about that....going paler? going darker? both? Lots of fabric auditioning and taking photos as you go is probably your best bet.
If all else fails, I am still willing to stump up for you to get that bucket of black dye
or just go with Nancy's advice