History problem on specific devices

Hi, 
I got some devices with a "/" in the hostname because there are switch
devices. 
For instance: GBWI-IDG-CSW08/10 or GBWI-IDG-CSW09/11 
When i click on each metric, then i click on "history" button, i always
got the msg:  
"Cannot open history file" 
On fs, the directory hostname doesn't exist in hist folder. 
What's wrong ?  
Thanks 
Regards, 
Nicolas Lienard