Sent folder not visible

Hi, I have had Thunderstorm on my old laptop for several years, and Sent folder is visible and working. Now I installed Thunderstorm on my new laptop, and Sent folder won't show up. I deleted Thunderstorm on the old laptop and reinstalled and Sent folder visible again. I've checked a lot of tips on this and followed them, please see screen dump below. All settings between old and new laptop look the same except the advice "Under place a copy in, choose the Sent folder" where it in my old one is checked with second option "Other place" and set on "myname/Infolder/Sent". When I move the mouse over "myname" and "Infolder" and then "Sent" appears and may be chosen. In my new laptop first option is set as default, and second option is available with "myname/Infolder", but "Sent" folder with its airplane icon is not visible and can't be chosen. Anyone know what to do? I appreciate all comments. Best regards, Torbjorn