fpga quartus error

on compilation following error is appearing .how to rectify it.

Error: Tcl error: ERROR: Illegal assignment: IP_TOOL_ENV. Specify a 
legal assignment name.

    while executing
"set_global_assignment -entity "pro" -library "lib_pro" -name 
IP_TOOL_ENV "qsys""
    (file "files/pro/synthesis/pro.qip" line 3)
  Info: set_global_assignment -name IP_TOOL_VERSION 12.0 -entity pro 
-qip files/pro/synthesis/pro.qip -library lib_pro
Error: Quartus II Analysis & Synthesis was unsuccessful. 1 error, 0 
warnings