Validation Required

Question

hello. I hope you are good in this pandemic saturation with your health. actually I make a signup form When I fill form by Correct like mobile no is 10 digit email id is correct format like that form is submitted successfully and data is added in database. BUT WHEN I PUT VALIDATION ON ALL FIELD WHICH REQUIRED VALIDATION IN MODEL.(I AM CREATING PROJECT IN MVC) SO REQUIRED VALIDATION IS NOT WORKING AND FORM IS GETTING ERROR. please tell me which condition Required validation is not working???? please suggest