Adding Inputs To Form - vue.js

Question

I'm using VueJS to have it dynamically add new inputs once a button is clicked. With my current code it is not adding the inputs. Why is that?
<div class="row" v-for="count in task.pos.length">
<div class="col-12 col-sm-6">
<div class="form-group">
<label class="control-label" for="po_number">Order Number:</label>
<input id="po_number" class="form-control" type="text" placeholder="Purchase Order" v-model="task.pos[count-1].purchase_order">
</div>
</div>
<div class="col-12 col-sm-6">
<div class="form-group">
<label class="control-label" for="po_amount">Order: Amount:</label>
<input id="po_amount" class="form-control" type="text" placeholder="Purchase Amount" v-model="task.pos[count-1].po_amount">
</div>
</div>
</div>
<div class="form-group">
<button class="btn btn-success btn-xs mb5 text-white" v-on:click.prevent="addEditNewPOEntry()"><i class="fa fa-plus"></i> Add PO</button>
<button class="btn btn-warning btn-block btn-xs" v-on:click.prevent="saveEdit(task)">Done</button>
</div>
addEditNewPOEntry: function(){
this.newTask.po.push({'purchase_order': this.task.purchase_order, 'purchase_amount': this.task.purchase_amount});
this.$set(this, 'task.pos.length', this.task.pos.length+1);
},