import the solidworks model into simulink simmechnical second generation ，something ERROR. why?

I am doing some model by solidworks2013 64bit and simmechnics second generation in matlab2012b now. I have some problem to consult you, when i import the *.xml into the simulink simmechnics second generation by 'smimport', i have export to second generation in solidworks,it always have error here like :

smimport('gripper_leg.xml')

Error using smimport_implementation (line 38)

Parsing the xml file failed. The input XML file is not a valid SimMechanics Import XML file.

Error in smimport (line 51)

hModel = smimport_implementation(xmlFile, varargin{:});

i don't know the reason,Thank you!