Permalinks Issue

Hi, I need to use this structure in my permalinks

/blog/%category%/%postname%/

It seams to work… but I go to the second page “http://wp.local/blog/mycategory/page/2/” , it crash and I see this in this in the page “I’m very sorry, but there is nothing here! Either the page you are looking for doesn’t exist, or the URL you typed or followed is incorrect or misspelled.”

How can I fix this?

Thanks in advance 🙂