CC2630: prompt failed message “Failed to halt after bootloader 1(or2) session aborted” when start download or erase cc2630 for debug

I'm develop with z-stack home 1.2.2a（with rtos） + cc2630F128RGZ 7x7 + xds100v3 + IAR FOR ARM 7.40. it is always work ok.

but I get failed frequently in downloading(or erasing) after downloading successed once or twice when I change target to board that designed by cc2630RHB 5x5 and change defined symbol MODULE_CC26XX_7X7 to MODULE_CC26XX_5X5. 

IAR show the message when failed:

Wed Jul 04, 2018 16:52:26: Loaded macro file: D:\Program Files (x86)\IAR Systems\Embedded Workbench 7.2\arm\config\debugger\TexasInstruments\CC26xx.dmac
Wed Jul 04, 2018 16:52:26: Loaded macro file: D:\Program Files (x86)\IAR Systems\Embedded Workbench 7.2\arm\config\flashloader\TexasInstruments\FlashCC26xx.mac
Wed Jul 04, 2018 16:52:27: Connecting to TI XDS100 (Probe no: FTFOP8Q)
Wed Jul 04, 2018 16:52:37: Fatal error: Failed to halt after bootloader 2 Session aborted!
Wed Jul 04, 2018 16:52:37: Unloaded macro file: D:\Program Files (x86)\IAR Systems\Embedded Workbench 7.2\arm\config\flashloader\TexasInstruments\FlashCC26xx.mac
Wed Jul 04, 2018 16:52:37: Failed to load flash loader: D:\Program Files (x86)\IAR Systems\Embedded Workbench 7.2\arm\config\flashloader\TexasInstruments

It will always fail if use IAR to download  when this problem is occur except use Flash Programmer 2 to download once. 

I can program successful the cc2630 with Flash Programmer 2 anytime. 

The problem is also exist when use the sampleSwitch sample project that only change the key and led driver gpio pin number.