First of all hello to everyone!

As you see this is my first post here.. I already read through this and other topics but unfortunately could not find any solution.. so here is my problem:
I used the mod on page 4 to implement the phpbb2 avatars... in comment_bit.html I added the following line:
{if comment_user_avatar} <img src="../phpbb2/images/avatars/{comment_user_avatar}"> {endif comment_user_avatar}
this works fine but as soon as someone who is not registered adds a comment right after a person who is registered and uses an avatar, the avatar of the registered person is also shown beside the post of the unregistered person..
i assume that I have to add something like " else <img src="../phpbb2/images/avatars/BLANK.GIF"> " but as I am a php noob I have no idea how to tell the script to link to a blank image as soon as a person is not registered or uses no avatar.. so I need your help

Sorry for my bad English.. i hope you understand what the problem is.. THANX