Button Click is not working on .aspx page ?

Question

Hi my url is https://www.mrnmrspet.com/dogs-for-sale/pali

I have an issue when i submit this form then the button is not working. and when i inspect the button then showing like this 

 

<input type="submit" name="btnNFSubmit" value="Submit" onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions(&quot;btnNFSubmit&quot;, &quot;&quot;, true, &quot;s&quot;, &quot;&quot;, false, false))" id="btnNFSubmit" class="btn btn-success">

 

validtions are working but after fill information button is not working. also I could not get textbox value in code behind. when i fill the newsletter email from this page then the email id value showing black to the code behind. please help me to resolve these above issues.

Thanks in advance