Last sector of flash root partition will not be flashed

[Hyphen79]

Hello,

the problem is, that the last sector of the mtd root partition 
(cramdisk) will not be flashed:

mtdblock: write on "File System" at 0x1f5e00, size 0x200
mtdblock: write on "File System" at 0x1f6000, size 0x200
mtdblock: writing cached data for "File System" at 0x1f5000, size 0x1000
mtdblock: write on "File System" at 0x1f6200, size 0x200
mtdblock: write on "File System" at 0x1f6400, size 0x200
mtdblock: write on "File System" at 0x1f6600, size 0x200
mtdblock: write on "File System" at 0x1f6800, size 0x200
mtdblock: write on "File System" at 0x1f6a00, size 0x200
mtdblock: write on "File System" at 0x1f6c00, size 0x200
mtdblock: write on "File System" at 0x1f6e00, size 0x200

But the last call to "write_cached_data" will not be done - even not 
after an explicit  "sync".
For example: "mtdblock: writing cached data for "File System" at 
0x1f6000, size 0x1000"
Has anyone an idea?