Cannot create return package

Question

We have 2 new members and they currently using the trial version of Trados 2017. I let them practicing to create the projects and send back return package. 
 However, both of them couldnt create return package. When I import their package sent to each other, I can create return package for them (mine is 2017 version, not trial one). 
 The function is greyed out. I searched from different sources for solutions but all doesnt work. Please help me! 
 Thank you so much!

Paul · Answer

Hi Do Xuan , 
 
Perhaps check the obvious first and make sure they are not logging into machines with the same user name. I saw this before in a classroom environment.

Trados Studio > 1. Trados Studio

Cannot create return package