If you're using a web form, remove via Form Options the ribbon buttons.
This often happens depending on how you are submitting the form data. A straight forward submit connection or with rules and code. Each process rule validation in a different order.
If I have lots of data which needs to be checked I have 2 buttons in 2 different sections.
1 section is for a mandatory check button, attacked to this button are rules for each field that I have to check against, also included is a field which I use to hightlght the name of an incorrect field. I also use conditional formatting too to show the field on the form. One this button has gone through all the rules, it then sets a field i.e. mandatory check = complete.
I include text in the visable section 1 so that my end users know that they must press the mandatory check button again after any changes.
Only when this field is set do I hide section 1 and show section 2 and the main submit button to the library.