ui-grid tooltip not working

Dear all,
I have the following issue trying to use ‘cellTooltip’ option in grid-ui.
Consider I have two columns and I would like to display mouseover tooltip on headers:
this.$scope.gridOptions.columnDefs = [
{
displayName: “Name”,
name: “name”,
cellTooltip:“TOOLTIP”,
enableCellEdit: false,
width: 150
},
{
displayName: “Name”,
name: “name”,
cellTooltip:“TOOLTIP”,
enableCellEdit: false,
width: 150
}

[quote=Tatyana Mastravchiyska]
Dear all,
I have the following issue trying to use ‘cellTooltip’ option in grid-ui.
Consider I have two columns and I would like to display mouseover tooltip on headers:
this.$scope.gridOptions.columnDefs = [
{
displayName: “Name”,
name: “name”,
cellTooltip:“TOOLTIP”,
enableCellEdit: false,
width: 150
},
{
displayName: “Name”,
name: “name”,
cellTooltip:“TOOLTIP”,
enableCellEdit: false,
width: 150
}
Question is: why the tooltip cannot be displayed? I have tried many workaround and nothing helps.