【求教】mwc编译出错

Arduino:1.6.5 (Windows 8.1), 板："Arduino Pro or Pro Mini, ATmega328 (5V, 16 MHz)"
MultiWii:67: error: variable or field 'SerialGpsPrint' declared void
MultiWii:67: error: 'prog_char' was not declared in this scope
MultiWii:67: error: 'str' was not declared in this scope
variable or field 'SerialGpsPrint' declared void
哪位大侠帮忙看看怎么回事了？（是不是因为没连GPS模块）