I bought a rose bus recently and it had buds on when I bought is but the bds won't open

The sun (!) usually does the trick as long as it is well watered.

Agree, but water is critical. If you planted in the ground, water thoroughly and frequently unless we've having torrential downpours every five minutes. Odd showers are no good, not enough to penetrate 8 inches down into the soil where the roots are. If its in a pot, water frequently too.