Ok, thanks Steve.
I have solved the problem. The problem was not in the MIC. Actually the datasheet did not clarify how to connect the MIC in SPI mode. I have connected the MIC in SPI mode in the same way connected in Standalone mode; except, the resistor which is connected to the -MIC should be connected to ground on the other end.Thats all the problem.

When they draw the design, they should have connected it to the ground directly , instead of connecting it to the REC pin; and that made a confusion.

Anyway, THANKS GOD. the problem is solved, and thanks again Steve.