[My first time(s)] Getting CM on my S7500 running

Hi together,
I'm stuck flashing my phone and don't know how to continue to solve this problem...
These are my first tries installing a custom firmware.

Here some details:

- Phone: Samsung Galaxy Ace Plus (S7500)
- Android: 2.3.6 (stock)
- CWM: 5.5.0.4
- Odin: 1.87
- CM: cm-11-20150201-UNOFFICIAL-trebon

This is what I did:
- Activated USB-Debugging
- Turned device off, restarted in Download-Mode (VOL down, Home, Power)
- Installed CWM with Odin (running Odin as administrator, virus protection disabled)
- Copied CM + gapps to SD root directory
- Turned device off, restarted in recovery mode (VOL up+down, Home, Power)
- Selected cm-11-20150201-UNOFFICIAL-trebon.zip
- Received Status 7 error
- Unpacked cm-11-20150201-UNOFFICIAL-trebon.zip, opened updater-script, removed the assert lines, saved, repacked cm-11-20150201-UNOFFICIAL-trebon.zip
- Recovery Mode boot, corrected CM selected, installation aborted (no details given)

Does anyone have a clue how I should proceed now?
I already installed a stock ROM and proceeded exactly the same way. Same behaviour. :rolleyes: