求救，F28069 SCI为什么进不了中断？

F28069 SCI初始化代码如下:

 EALLOW;
 GpioCtrlRegs.GPAPUD.bit.GPIO28 = 0;    // Enable pull-up for GPIO28 (SCIRXDA)
 GpioCtrlRegs.GPAPUD.bit.GPIO29 = 0;    // Enable pull-up for GPIO29 (SCITXDA)

 GpioCtrlRegs.GPAQSEL2.bit.GPIO28 = 3;  // Asynch input GPIO28 (SCIRXDA)
 GpioCtrlRegs.GPAMUX2.bit.GPIO28 = 1;   // Configure GPIO28 for SCIRXDA operation
 GpioCtrlRegs.GPAMUX2.bit.GPIO29 = 1;   // Configure GPIO29 for SCITXDA operation

 GpioCtrlRegs.GPAPUD.bit.GPIO23 = 0;    // Enable pull-up for GPIO23 (SCIRXDB)
 GpioCtrlRegs.GPBPUD.bit.GPIO58 = 0;    // Enable pull-up for GPIO58 (SCITXDB)
 GpioCtrlRegs.GPAQSEL2.bit.GPIO23 = 3;  // Asynch input GPIO23 (SCIRXDB)
 GpioCtrlRegs.GPAMUX2.bit.GPIO23 = 3;   // Configure GPIO23 for SCIRXDB operation
 GpioCtrlRegs.GPBMUX2.bit.GPIO58 = 2;   // Configure GPIO58 for SCITXDB operation
 EDIS;

 SciaRegs.SCICCR.all =0x0007;      // 1 stop bit, 8 char bits,
 SciaRegs.SCICTL1.all =0x0003;     // enable TX, RX
 SciaRegs.SCICTL2.bit.RXBKINTENA =1;
 SciaRegs.SCIHBAUD = 0x01;
 SciaRegs.SCILBAUD = 0x03;    //baudrate set 9600

 SciaRegs.SCICTL1.all =0x0023;       // Relinquish SCI from Reset

中断也使能了，可是就是进不了中断？