Bootloader running from Flash

Hi,

I am currently working on the XCM4700 Relax Kit.
The Flash bootloader is located in the range 0x0800000 - 0x0801000

The bootloader is allways started at power up and should check the application in the range 0C010000 - 0x0C17FFFB and compare it with a checksumm located at 0x0C17FFFC - 0x0C17FFFF (last double word in Flash sector).

The Flash bootloader was developed from the ascLoader (bootloader in Flash and XMC4000 Flash functions are copied to psram) and uses the same communication protocol.

My problem is the erasing of the last Flash sector 0x0C140000 - 0x0C140000 for programming the application checksum.

Sending the following uart frame
hex command for erasing sector S13: 00 03 0C 14 00 00 00 04 00 00 00 00 00 00 00 1F
Returns succes, but checking the flash sector show that is wasn't erased correctly.

Erasing another sector
hex command for erasing sector S4: 00 03 0C 01 00 00 00 00 40 00 00 00 00 00 00 4e
erases the Flash sector correctly.

I hope someone has experienced something similar or can help me.