This was my understanding --- actually I designed the licensing structure of this project around the assumption that companies would not want to use GPL licensed code commercially. I offer an AGPL license, and offer a commercial license for a fixed fee.

My understanding is that if you link to the library, your code must also be GPL, which means that anyone linking to your code must be GPL, etc.

This is a problem if you're trying to sell your code. Probably you don't want to make it GPL, and you probably don't want to force your customers to make their code GPL.