When you complete an entry form as a member of England Athletics (EA) the system runs a check on the EA membership database. It does this using the values you provide for membership number, first name surname and date of birth. If the validation fails it means that the details you provided do not match to a current member of EA.
You can run a check yourself on the membership database. Go to
ea-registration-check.myathletics.uk. If the check is successful please make sure that you use the correct values on the Racesignup entry form. If the check is not successful, you will see an email address on that page and can ask for assistance by sending them an email.