帮忙！！关于ise5.0下无法仿真的问题

请问：我安装的是XILINX公司的ISE5.0的。但无法仿真。我安装了MODULSIM6.0。出现如下解释。不知该怎样解决？
Unable to back annotate,the most common reasons are:
1) The external simulator needs to be closed to unlock the annotation file.
2) The annotation file does not exist because the annotation test bench has not yet been
simulated
Annotation file=c:\mydesign\tour\counter_tdw.ano

有人回答了吗？我也有相同的问题

可能是你开了2个仿真窗口，关掉原来的重新开试一下