Hi Albert,
I guess you are currently using the 'IP' image (c2600-i-mz.122-15.T14.bin) ?
For that release, you either need the 'IP Base image without switching' (c2600-is4-mz.122-15.T14.bin) or the 'Enterprise Basic' image (c2600-j1s3-mz.122-15.T14.bin) .
cheers,
Seb.