Import Motion loads error

Hello,

I have an assembly, I wanted to study the stress during a motor and external load. I did motion analysis for the system. Hence, I used  import motion loads with multiple frame to study the each part individual. It works for all the parts except one part. The follwing error pop up when I try to import motion loads "Could not create attribute data CMI-ALT DSGNSCN-DATA-S: Special loads...." and this special load error appears by the number of frames. Could you help me to knw what is this error?

Many thanks

SolidworksMotion Studies