Hi pedromiguelpg,

Can I ask which error do you receive? and could you please be more specific with your scenario? 

Best regards,

This is my scenario

Item List

I tray to use the webservice _vti_bin/K2SpFiles.asmx  witch the method ApproveDocument(), dont work, because isn´t a file.

Now i dont find another method to approve itemslist in sharepoint witch K2 process.

The K2 supplied web services really aren't meant as a public API.  They implement some of the behind-the scenes functionality used by the product.  I'm not sure what you mean by approving the document.  Perhaps a native SharPoint web service API would be the way to go.