To Answer My Question, There Is Only One "tmp" Folder In The Installation Directory
Aaargghhh..... (you will never find the problem if you dont read the answers and follow instructions).
A very very very last hint: tmp directories are ALSO part of all Operating Systems, and these tmp directories are DIFFERENT from that in your installation folder. Configuration parameter (as found in php.ini for example) are responsible for the decision, WHICH of the known tmp directories are finally used by the software. Very often this is a tmp directory of the Operating System and NOT the tmp folder in a software installation.
Got it now? If not - I give up anyway.