I build a repeating unit of CH2-CH2 for the polyethylene, and then optimized using Forcite, save it by clicking File...Save. Then goes to Synthia, select Homopolymer, and go to repeating units, select the current project, and the OK button never becomes available.

I was alerted that the repeating unit must be vailid, and appraently it is. The repeating unit must be saved, and apparently I did.

Can anyone help me out please? It has bothered me all day  long.

I appreciate your help!