I am a graduate student in Computer Engineering an am developing some small VHDL modules targeted to Xilinx Virtex devices. While I was trying to synthesize some of those designs using synpliciy I got the following error." Invalid LUT instantiation. Have you included the virtex.v(hd) file, and an INIT value @E:Internal Error". I tried adding virtex.vhd from synplicity installation library and tried to re synthesize it and now I see an error " Undefined identifier" and it does not even point to the module which causes this. I have read in some other postings in this group that one should not include unisim libraries while synthesizing using Synplify pro 7.7. I have in fact tried both ways (including and excluding unisim libraries) but the above error persists. I would appreciate if anyone can suggest where I am doing wrong.