这条路径约束ise死活不分析，咋回事？

kaiseradler

NET"Sdram_Clk"TNM_NET = "Sdram_Clk";

TIMESPEC TS_Sdram_Clk = PERIOD "Sdram_Clk" TS_SysClkIn /5 PHASE -1 ns HIGH 50%;

TIMEGRP "sdram_data" OFFSET = OUT 2 ns AFTER "Sdram_Clk" ;