I receive the submission but paypal doesn't go through

I have checked your submissions and I saw that some of them have have payment details and some of them don't, because non of the products were selected. If non of the products are selected your users will not be redirected to PayPal to complete payment. 

To avoid that you need to set your Paypal payment field to be required. 

Hope this will help. Let us know if you need further assistance.