ERROR:Pack:1107 - Unable to combine the following symbols into a single IOB

qlengyu

ERRORack:1107 - Unable to combine the following symbols into a single IOB
   component:
    BUF symbol "lcd_data_7_IOBUF/IBUF" (Output Signal = N2091)
    TBUF symbol "lcd_data_7_IOBUF/OBUFT" (Control Signal = lcd_data_not0001_inv)
    PAD symbol "lcd_data<7>" (Pad Signal = lcd_data<7>)
   Each of the following constraints specifies an illegal physical site for a
   component of type IOB:
    Symbol "lcd_data<7>" (LOC=P97)
   Please correct the constraints accordingly.

MAP过程中报以上错误，好像可以通过修改工程的属性可以解决此问题，但是不知道具体修改哪些参数，请高手们指点。

板子已经做好，所以改管脚是很麻烦的。
lcd_data的数据类型是inout
LOC=P97 管脚的类型是IO/VREF