Please delete adxloader.dll from c:\Program Files\Wasp Technologies\BarcodeMaker, then download a new copy of it from https://dl.waspbarcode.com/kb/bcm/adxloader.zip and extract it to the same directory.
If the error persists after replacing the adxloader.dll, you may need to reload .Net Framework 4. Please download the full setup from Microsoft to reinstall: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=17851