ng-model没有更新select中的选择更改

Hi I am new to angular so still struggling with basic things, here is a problem that I am facing. I have a few html elements that repeat with ng-repeat. One of the controls in it is a dropdown. I have attached ng-model with this .However on selection change the model is not getting updated.Not sure what the problem is. Pasting below the code.Hi I am new to angular so still struggling with