Ion-select Ok button not triggering ionChange event if nothing is selected in select box

I am using ionic 3.2.0 version. If nothing is selected in select box and Ok is clicked, its not triggering the ionChange event.

I am trying to mark the control as touched when nothing is selected in the select box.

I am able to do it for Cancel button using ionCancel event but on selecting nothing and clicking Ok button, ionChange is not triggered.

Please advise!

Thanks!

Jinisha

“dependencies”: {
"@angular/common": “4.1.0”,
"@angular/compiler": “4.1.0”,
"@angular/compiler-cli": “4.1.0”,
"@angular/core": “4.1.0”,
"@angular/forms": “4.1.0”,
"@angular/http": “4.1.0”,
"@angular/platform-browser": “4.1.0”,
"@angular/platform-browser-dynamic": “4.1.0”,
"@ionic-native/core": “3.6.1”,
"@ionic-native/splash-screen": “3.6.1”,
"@ionic-native/status-bar": “3.6.1”,
"@ionic/storage": “2.0.1”,
“ionic-angular”: “3.2.0”,
“ionicons”: “3.0.0”,
“rxjs”: “5.1.1”,
“sw-toolbox”: “3.6.0”,
“zone.js”: “0.8.10”,