Assembler error while using alt_dqdqs in a custom DDR2 PHY

i have implement a custom ddr2 phy using alt_dqdqs megafunction, but when i compile it in quartus, quartus report a error during Assembler stage, looks like:

Internal error: sub-system: ASMCC

File: /quartus/......

Assembler bitfield error:

Found conflicting assignment for CFF address.

I found a patch in Altera website, but that patch is mainly for Altera MEMPHY and DDR2 controller using ALTMEMPHY, not for alt_dqdqs.

I try quartus version 9.1sp2 10.0sp1 and 11.0, they all have the same error.

Any solutions?