Hello Kashif,

Thank you for contacting Infragistics Developer Support!

This is not working because:

1. The markup you have provided is invalid - the input element should not be closed and does not have content, i.e. <input id="cbDb" data-bind="igCombo: { width: '160%' }, tooltip: { title:'register' , trigger: 'hover'}" type="text"> </input> (refer to this => http://www.w3.org/TR/html401/interact/forms.html#h-17.4)
2. The provided input is not valid input element. You can see the valid input type here => http://www.w3.org/TR/html401/interact/forms.html#h-17.4.1. The correct way to initialize the control is to use either div or a span element.
3. The value of data bind is incorrect it should be data-bind="igCombo {  width: '160%' , tooltip: 'register', tooltipTrigger: 'hover'}", i.e you should specify all bindable properties in one pair of curly brackets.
4. There are no methods or options for the combo for tooltip or tooltipTrigger, so this is not going to work still. (please refer to the following => http://help.infragistics.com/Help/Doc/jQuery/2014.1/CLR4.0/html/igCombo_KnockoutJS_Support.html#_Ref349582658, http://help.infragistics.com/jQuery/2014.1/ui.igcombo#options)

Before I can be able to provide you working sample I need you to specify what of the following you are trying to achieve:

       *  You want the combo to have tool tip bound to view model property, i.e. when you hover over the combo and a tool tip is displayed.

       *  You want each item in the combo list to have tool tip bound to view model property, i.e. when you hover item from the combo list and a tool tip is displayed for the corresponding item.

Thank you in advance I will be waiting for your feed back!