For Dynamic .NET TWAIN v6.x and lower versions only, for V7.x+ please refer to http://developer.dynamsoft.com/dnt/kb
Symptom:You are trying to use Dynamic .NET TWAIN and are seeing the error: Your Licenses number for the "Module name" doesn't exist or it's invalid.

Solution:
For .Net TWAIN 6.0 and above
For core SDK and add-ons except barcode reader
Define the license key in your code as follows:
dynamicDotNetTwain1 = new DynamicDotNetTwain("XXX;YYY");
For barcode reader add-on
Please refer to this KB.
For .Net TWAIN 5.x and below
1. Delete the .licx file from the project.
2. Define the license key in your code as follows:
dynamicDotNetTwain1 = new DynamicDotNetTwain("XXX;YYY");
For any questions, please contact support[at]dynamsoft.com