form state changing to $invalid after submit - angularjs

Question

I don't understand and have done lot of research to no avail. After I hit submit button, my form state changes back to $valid = false. This causes the input controls to go RED. How do I fix this. Here is my code.
<form class="form-horizontal" role="form" name="testMessageForm" novalidate>
<div class="form-group"
data-ng-class="{'has-error':testMessageForm.PhoneNumber.$invalid && testMessageForm.PhoneNumber.$dirty}">
<label class="col-sm-3 control-label" for="Phone">Cell Number</label>
<div class="col-sm-9">
<input required
placeholder="nnn-nnn-nnnn"
ng-pattern="/^(\([0-9]{3}\) |[0-9]{3}-)[0-9]{3}-[0-9]{4}$/"
minlength="10"
maxlength="14"
data-ng-model="reminderTest.PhoneNumber"
id="PhoneNumber"
name="PhoneNumber"
class="form-control" />
<span class="help-block has-error">
<span ng-show="testMessageForm.PhoneNumber.$error.required">
required
</span>
<span ng-show="testMessageForm.PhoneNumber.$error.minlength">
At least 10 digits.
</span>
<span ng-show="testMessageForm.PhoneNumber.$error.maxlength">
Why so many characters. Double check.
</span>
<span ng-show="testMessageForm.PhoneNumber.$error.pattern">
Wrong Phone number pattern.
</span>
</span>
</div>
</div>
<div class="form-group">
<label class="col-sm-3 control-label" for="Email"></label>
<div class="col-sm-9">
<button class=" btn btn-success"
type="submit" value="Test"
data-ng-disabled="testMessageForm.$invalid"
data-ng-click="submitTestReminderForm()">
Test Reminder Now
</button>
</div>
</div>
<div data-ng-show="loading == true">
<div class="spinner">
Loading...
</div>
</div>
<div class="alert alert-success" data-ng-show="successMsg.length > 0">
×
<strong>Great! </strong> {{successMsg}}
</div>
<div class="alert alert-danger" data-ng-show="errorMsg.length > 0">
×
<strong>oops! </strong> {{errorMsg}}
</div>
</form>
Controller code.
$scope.submitTestReminderForm = function () {
reminderService.insertTestReminder($scope.reminderTest).then(onReminderTestComplete, onReminderErrorTest);
};
Service code
var insertTestReminder = function (reminderTest) {
return $http.post("/api/ReminderTest", reminderTest);
};