Inspiron 6400 model number for the primary battery cannot be determined

I work as a support engineer for a large computer company, we have a lot of Dell notebook systems and therefore get through a lot of the batteries. The last batch we brought came through as Dell part number JN149 they all seem to work fine in the Latitude 131L systems, the Inspiron 1501's and the Vostro 1000's. However when i try putting them into our Inspiron 6400 systems they all come back with this error message after the Dell Splash screen,

"WARNING: The model number for the primary battery cannot be determined.
This will prevent any battery present from charging. Please insert a Dell
battery for best system operation."

These batteries came through direct from Dell so i know that they are genuine, we have had this part number come through before and all of the last batch work fine in the 6400's so I'm sure it isn't a part number issue. I have tried flashing the bios to the latest version and even downgrading the bios to an earlier version to see if this solves the issue but as yet neither of these have had any effect.

I was wondering if anyone else has come across this problem and if anyone knows a fix?

Thanks

Dan