MSP430FR5989: Setting P2.1 (TB0.5) to enter capture mode does not take effect and does not enter interrupt mode

Part Number: MSP430FR5989

I want to use the capture mode of MCU P2.1 as TB0.5 to capture the pulse width of the input waveform, but mcu didn't enter the interrupt function. The following is my configuration code：

{

P2DIR&=~BIT1;

P2IES|=BIT1;
P2IFG&=~BIT1;
P2IE|=BIT1;

TB0CCTL5 =CM_3|CCIS_1|SCS|CAP|CCIE;
TB0CTL = TBSSEL__ACLK | MC__CONTINUOUS ;  // ACLK, Continuous up

}

Please help me analyze what is the problem.