The request do not open on the replacement engineer

The request do not open on the replacement engineer

Good day,
the request do not open on the replacement engineer. The engineer goes on vacation, puts the substitution in the calendar, his the requests in the status of awaiting response. The user responds to the request, but it is not transferred to a replacement engineer, the request is opening to the engineer, who is on vacation. 

How to fix this problem?

PS. If i want to appoint the request for the engineer who is on vacation, the system automatically substitutes the replacement engineer.

Sevice desk:
Our version : 9.3 Build 9301
Data base : postgres

Server service desk Ubuntu 12.04.3 LTS
kernel version 3.8.0 - 29-generic

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