The IsValid property always return false doesn't matter what license fields are included to the license.

There are 4 possible cause of invalid license.

1. License have not passed protected product validation. Check that AssemblyCompany, AssemblyProduct, AssemblyVersion, AssemblyFileVersion attributes in the AssemblyInfo file have equal values with information entered for the Product (Product name and Company) and Version (Major, Minor, Build, Revision) definitions in the License Manager. Our licensing system uses these attributes to check if the license file is used for the right product. If it is not so IsValid return false anyway.
2. License file have not any validation rules. License type should contains at least one validation rule (format).
3. One of the license rules (formats) have not passed validation. You can check what rule have not passed validation using 'IllegalValidator' property of the license object.
4. The problem also can be in the old Unlock Key format saved in the protected storage. If you've changed "Unlock Key" format in the version node you have to clear protected storage in order you application accept new Unlock Key. Right click version node in the License Manager and select "Clear Protected Storage" from the context menu. You also should recreate license file in this case.