@hui @malcolmlewis
Thank you for your support! Now it works. 
Finally i deleted the current program and made a new installation.
When looking after the libtiff-files i got this:
lrwxrwxrwx 1 user user 16 17. Jan 20:56 libtiff.so -> libtiff.so.6.0.0
lrwxrwxrwx 1 user user 16 17. Jan 20:56 libtiff.so.6 -> libtiff.so.6.0.0
lrwxrwxrwx 1 user user 16 17. Jan 20:56 libtiff.so.6.0 -> libtiff.so.6.0.0
-rwxr-xr-x 1 user user 559240 11. Jan 14:47 libtiff.so.6.0.0
Then i checked the ELF version from libtiff.so.6.0.0
user@ln-sg-vpn1:~/dm/dm-Fotowelt> readelf -h libtiff.so.6.0.0
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
When starting the program i got this error
user@ln-sg-vpn1:~/dm/dm-Fotowelt> ./dm-Fotowelt
./dm-Fotowelt: error while loading shared libraries: libtiff.so.5: cannot open shared object file: No such file or directory
Then i made the symbolic link
user@ln-sg-vpn1:~/dm/dm-Fotowelt> sudo ln -s libtiff.so.6 libtiff.so.5
Now it is working 