Zoho IM Function in Zoho Mail/Dashboard

Zoho IM Function in Zoho Mail/Dashboard

when I use Chrome, i do not have problems sending IM chats to other staff.  but others who use internet explorer cannot send or reply.  When I hit enter on Chrome it sends out the reply/msg.  When they hit enter in ie, it returns and goes to a new line.  

how can a user of ie use the chat function within the zohomail dashboard?