Problem with /writedisk

I try to put my SDI file on my USB drive and not sure if I fallow the
write step sinc eI got a strange error.

First thing first.

When i go in Diskpart, I don't see my USB drive as a DISK but as a
Volume. Is this a problem?

To try to put my SDI file on my USB key I do this:
1- I check if my SDI does have a DISK blob and it does.
2- I try the command :

sdimgr c:\sdi\MySDI.sdi /writedisk:2 /yes (since my USB key volume is
#2)

When I start it I got this output:

*Writing to disk : "\\.\PHYSICALDRIVE2"...
Error -2147467259 <0x80004005> in "SDIAUT.SDIFile.1": The system
cannot find the file specified.


I thought that the path to my SDI or the SDI name was incorrect but if
I only type sdimgr c:\sdi\MySDI.sdi I got the /dump equivalence.

I really don't know what this error mean..

Thanks for help,

Fallow up,

I did correct this error. I went in the Computer Management and saw
that my USB Key had the DISK #1 and the write was done correctly.

After that, I did other test and I currently have 2 problem.

1- I got a 1GB USB key and when I write my SDI file in it (which is
380meg) my USB key size change to 380meg. This is correct and I accept
it.
The problem is after that, I do a little change in it (adding 1
software) and I use /READPART to create a new SDI file. The new SDI is
created but
his size is 1GB when it should normaly be 380meg!

Why when I use /READPART , the SDI take the original size of my
USB key and not the size of the USB key take after the /WRITEPART ??


2- My original SDI file only contain a PART Blob which is correct for
me but when I try to do a update on it using SDILOAD, the PART Blob is
change to a DISK Blob.
What I do is:
- Create a Virtual Drive using SDILoader which is 390meg.
- I put my Original SDI file into the virtual drive using /
WRITEPART
- I do my modification (adding 1 little software)
- I unload the Virtual Drive
- I find my new SDI file that contain my modification with a good
size BUT this new SDI file only have a DISK Blob. Why ?

Thanks,

Any help on that ?

I'm also wondering if I really need the BOOT and LOAD Blob to be able
to boot from a USB drive?

Thanks,