Shell-solid contact error

hi all,

 

I came across an error during the acoustic analysis. the problem seemes to be in FREEZ contact between the solid faces of the acoustic medium and shell faces of the structure. the contact is as such

 

 *** ERROR # 1904 ***
 SURFACE 13 refers to element 136350 of incorrect type.

 

If I turn off the contact the simulation works fine

 

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

 

 

SSID are solid surfaces of the solid part and MMID are the shell surface of the shell parts.

 

thanks for help in advanced.

 

Regards,

 

Uroš