Tax issue

Hi all,

I'm trying to post an idoc , iam getting a message code 51 saying

G/L acount 12897 is set not relevant to tax.

We use a 0 tax for all G/L accounts. When i go to FS00 and under control tab if i set * for tax category and check the box post without tax , it doesn't throw me an error.

We have 2000 G/L accounts, i can't go to FSOO for each G/L account and set it there.

We are upgrading from 4.6c to ECC 6.0 and in 4.6c it is not set in FSOO an it doesn't throw an error.

So my questions are

1) why i need to set it in ECC 6.0 in FSOO , though it is not needed to do in 4.6c

2) Is there a way that i can set the tax to 0 for all G/L accounts in a single time

3)i followed this path

IMG > MM > Invoice verification > Incoming invoice > maintain default values for tax codes

The company code to which all this G/L accounts belongs has a tax code of IO in both the version

But for some reasons i get error in ECC 6.0

Let me know

Thanks

Venki