Check all parts again. Maybe one of the parts isn't properly installed. I don't know the tools names. If the tool on the left upper side isn't working as it should the ps2 thinks that the lid was opened (which you're trying to prevent with the "Swap Magic" tools) and the swap won't work.
Where did yout get your discs from ? On both disc should be the same logo and text for the "Swap Magic" and on one the logo for DVD and on the other the logo for CD.
The coder disk has a feature to cheat your game with "Action Replay" codes.
For swapping a DVD-based game you must use the "Swap Magic" DVD.
PS2 SCPH-70004 V12 PAL + HDCOMBO + 160 GB Samsung HDD + OPL 0.9.1
PS2 SCPH-70004a V13 PAL Satin Silver
2 x Official Sony 8mb card +FMCB 1.8c + uLE 4.42b
Datel Max Memory 32mb card +FMCB 1.8b + uLE 4.42
Memor32 + Memento FW 1.2e