[capink]

It is working for me. Note that k2pdfopt options can be mutually exclusive. So for example if you try specify margins while at the same time you using default conversion mode, margins will not be trimmed, even with the command line program. You can use trim mode instead and you will be able to crop margins.

At the bottom of the plugin's dialog there is button called "Show command version" that opens textbox, you can copy/paste the textbox here so that we can see what options you are using.

It is helpful to both read k2pdfopt documentation, and also experiment with the command line program using the content of the textbox above, to examine whether there is any discrepancy between the plugin and the original program.

Edit: The plugin already greys out some options when they clash with other selected options. This obviously does not cover every possible clash. After we got to the bottom of what your problem is, I will see whether I can grey out the margins box in certain scenarios.