In Drupal, sometimes when you add the appropriate permissions for a user to be able to edit a node you are surprised when no edit tab comes up and if you navigate to the edit URL directly you get an "access denied" error.
If you think you have added the permissions correctly and cleared all the relevant caches, the following may help you solve your problem. It turns out that you may not have added the permissions correctly after all.
The issue may be that the user you are trying to use to edit the node does not have the permission to edit using the input format that the node uses.
That is, if a user is permitted to edit a node which uses the "Full HTML" input format, but the user himself is not permitted to use "Full HTML", then he will not be allowed to edit the node at all.
1. From the root user's account, check what input format the node uses.
2. Go to Site Configuration > Input Formats (located at /admin/settings/filters) and then make sure that the corresponding input type is configured to allow the role of the user (that you are permitting to edit the node) to use that type.
This problem usually occurs when a node is configured to use "Full HTML" as the Input Format and since users aren't permitted to use that Input Format by default, you will get the problem.
We hope this Drupal tutorial was useful.