Backend view picture thumbnail not generated

[wolfgang007]

Hello guys,

I have set the following lines in constants:

plugin.tx_powermail.settings.misc.uploadFolder = fileadmin/user_upload/powermail/ plugin.tx_powermail.settings.Pi2.misc.file.folder = fileadmin/user_upload/powermail/

... and the pictures get uploaded correctly ...

But in the backend detail view of the mails I get no thumbnail only "File does not exist". If i click on it, I get the right Picture.

Any ideas? Is this a bug? Is there a config in TCEMAIN necessary?