no.range in billing

Dear All

After creating invoice when doing VF02 to release to FI.

Error throws as 01 number range for year 2008 not there.

I have been trying in T.code FBN1 to create new no. range but always no. range overlapes and there is no space.

I have deleted all past years 01 no.range and creating for 2008 but still overlapping problem is there.

Pl. any one help

regards