Unknown Runtime Error

With this I get an Unknown Runtime Error,
Anyone sees anything wrong in this 3 lines?

function delete(number,block) {
document.all["block" + number + "" + block].innerHTML = ""
}

a minor adjustment which may or may not work ...

function delete(number,block)
{
var sId = "block" + number + block ;
document.all[sId].innerHTML = "" ;
}

actually, "delete" is a reserved word, so you can't use it! :)