The problem is most likely that there is an error in a different view. For example if you have 3 views and 3 required fields in your form template, and each view contains only one of each of the required fields... then no matter which view you are on, you are only seeing 1 of the required fields. Thus if you fill it out and try to sign/submit, there are still 2 other required fields that haven't been filled out because the user can't see them since they are on the different views.
To work around such issues, you have to set the fields as not required in your data source, and then add custom data validation to the fields in the views such that they are only required when that view is active (you'll need some field to identify which view, or state, your form is in for this to work).
That's a broad overview, but should give you some idea what's likely going on.