1- Brd cross-section: L1(sig)/L2(Vss)/L3(Vcc)/L4(sig)
2- Set L2 and L3 as negative plane
3- Draw "Shape-> Rectangular" on L2, and assigned net "Vss" successfully
4- Define padstack sucessfully
5- Netin successfully
6- Place successfully and export .dsn file.
7- Load *.dsn to Allegro PCB Router XL
8- Route Vss net of L1 connecting to L2 plane by "Add via", but failed, as no "Via" between L1 and L2 can be used!!
The via appears ONLY connecting L1 to L4 can be used.
Anyone who can tell me what I miss, how to resolve this problem? Thanks a lot.