Keil ARM Nuvoton Controller

Hi All.

I am working on a project where i am using Nuvoton NUC029LAN Microcontroller. 

in the code when i assign any value to any port, for example.

P2 = 0x00;

i am getting an error which says, 

main.c(102): error:  #137: expression must be a modifiable lvalue

can any body please let me know what the error is for.