Following information taken from: https://knowledge.kofax.com/Capture/Kofax_Capture/Reference/Validation_script_field_is_not_executing_default_behavior
Issue
I am implementing a Field's Postprocessing event in a Validation script. This is causing certain default behaviors, such as Field Length checks, etc., to not occur when in the validation module.
Cause
Implementing a Field's PostProcessing event in a Validation script overrides the default behavior of the Field.
Solution
Add a call to the DefaultFieldPostProcessing() method in the FieldPostProcessing event handler to perform the default post-field processing of the current index field.
The current index field is validated based on its data type and a ValidationErrorException is thrown if the validation fails.
Example:
Private Sub Name1_FieldPostProcessing(sender As Object, e As PostFieldEventArgs) Handles Name1.FieldPostProcessing
Name1.DefaultFieldPostProcessing()
End Sub