Live connection with matlab

Hi every one

i am working with live connection comsol with matlab . when i want to make optimization by using optimization tool for 7 variable on my model . after some time of working it gives me this error

(line 143)
Java exception occurred:
Exception:
com.comsol.util.exceptions.LicenseException: Could not
obtain license for X Required product#Terminal 1#AC/DC
Module
(rethrown as com.comsol.util.exceptions.FlException)
(rethrown as com.comsol.util.exceptions.FlException)
Messages:
Could not obtain license for X Required product#Terminal
1#AC/DC Module

Could not obtain license for X Required product#Terminal
1#AC/DC Module

Could not obtain license for 'Terminal 1'.
Required product: AC/DC Module.

License error: -15.
Cannot connect to license server system.

i have the license for comsol 5.2 and matlab 2015b, i don't know why ?
can anyone help me with this problem


thank you