Scroll for background is not working - css

Question

I am implementing a chat module like linked-in or facebook. User List is one parent component (col-md-12) and after each user click, I am creating a new child component (col-md-3 each). Everything is working fine but the scroll option on (col-md-12) is not working. The position of parent and child component is fixed hence the background scroll is only working if I scroll outside col-md-12 class area.
<div class="row" >
<div class="content">
<div class="row">
<div class="col-md-12" id="ng-chat-view">
<div class="col-md-3 chat-farmer-list-ui">
<div id="ng-chat-people" [ngClass]="{'ng-chat-people-collapsed':isCollapsed}">
<a href="javascript:void(0);" class="ng-chat-title shadowed" matTooltip={{farmerListTooltip}} (click)="onChatTitleClicked($event)">
<span>
Farmer List
</span>
</a>
<input *ngIf="!isCollapsed" id="ng-chat-search_friend" type="search" placeholder="Search" [(ngModel)]="search" (ngModelChange)="getFarmerBySearchVal(search)"
/>
<ul id="ng-chat-users" *ngIf="!isCollapsed">
<li *ngFor="let user of farmers">
<div *ngIf="!user.imageUrl" class="icon-wrapper">
<i class="user-icon"></i>
</div>
<img *ngIf="user.imageUrl" alt="" class="avatar" height="30" width="30" src="{{user.imageUrl}}"/>
<strong title="{{user.user}}" (click)="openChatWindow(user, true)">{{user.name}}</strong>
</li>
</ul>
</div>
</div>
<div class="col-md-9 m-l">
<div *ngFor="let user of userInfo; let i = index">
<div>
<app-chatwindow [userInfo]="user" (onWindowCloseNotify)="onWindowCloseInChildComponent($event)"></app-chatwindow>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
CSS:
#ng-chat-view{
position: fixed;
bottom: 0%;
margin-right: 10px;
font-family: Roboto,RobotoDraft,Helvetica,Arial,sans-serif;
font-size: 15px;
z-index:999;
cursor: pointer;
}
.row .m-l{
margin-left: -92px;
float: left;
}
#media (min-width: 992px){
.chat-farmer-list-ui {
float: right;
}
}