can't access shared folder with read write permissions

At the office I've noticed that I can't access certain windows folders even if the permissions are set to read / write. This seems to happen to folders my co-workers have added. When someone else on a mac adds a folder I can't add files to it. When I add a folder myself, this co-worker can add files but he on his turn can't add files to folders co-worker number 3 had added. When I view all folders with Info I can see that permissions are set to read/write, so we should be able to save something to folders we haven't added ourselves. I can add a folder myself and add something to this folder. IT has checked the network drive in question and we should have complete access to the entire network drive. What could be wrong?

 

I don't know how it's formatted but I guess the same way other network drives at work are formatted. On which I have no problem.

The funny thing is that I CAN write to some folders. But for example not to folders user2 has created. User2 can create a folder and add files to it. User2 can also add files to folders I (user1) have created. User1 (me) can't add files to folders user2 has created. User2 however can't add files to folders user3 has created. I however can add files to folders user3 has created. Make sense?

It seems to be user dependent. I can't add files to user2 folders but can add files to user3 folders. User2 can't add files to user3 folders but can add files to user1 folders. But each user can off course add files to his own folders.

Somehow when creating a folder a user adds his permissions while creating the folder so it seems? And even if Info says read/write only the user who created the folder can add files to it? Or at least some other users can while again other users can't?

I've also tested it on a pc to see what happens, but there it's the same thing. Can't add files to certain folders of other users there too.