Does the new growth appear to have a white powdery substance on them? If so, your rose could have powdery mildew.
Or - do the buds appear brown and dry on the outside? Has it been rainy? The buds may be 'balling' because they are too wet. Sometimes you can carefully remove the outer petals and the bud will open up properly.
Or - do you see small white insects around? You could have thrips. Then you could spray just the buds with an insecticide or insecticidal soap.