can't access safari with parental controls on

[Sabrina2000]

I've just created a user account for the kids, and I am not blocking any websites at all, but am restricting time; safari is allowed. But every time we go into kids account the safari icon shows up as a grey question mark sign and there's no safari access......can anyone help? we want to give unrestricted internet access, but with time limits. Have set time limits but still no safari, despite checking the box to allow it.