If your modchip accepts the format that you've been burning (DVD+/DVD-/CD-R etc) then you should just be able to burn it normally. Nero should do the job, but for DVDs i would advice using DVD Decryptor.

DVD Decryptor can Burn ISO image files straight the the DVD, but it also has the Brute force method as well in the event that your DVD-ROM dosn't recognise the data stream. If Nero failed, it's likely your DVD Writer failed to recognise the stream properly, and burned it using the wrong method. For instance, if it's RAW information, which most consoles use, it's unlikely that your PC will understand this information and your DVD Drive will fail to burn it properly.

The DVD Decryptor uses Brute Force on occasions like this, where it burns in Binary Form (Each individual 1 and 0). However for this method to work correctly you need to leave your computer with as few processes as possible and burn very slowly to make sure it gets the info down correctly.

Incidentally, this program is also the best program for making DVD Images onto your PC. You can download it for free Here.

Unfortunately, i don't have too much experience myself with this sort of thing. So if DVD Decryptor is unable to burn it properly, i don't know how to help you on this matter.

Oh and btw, make sure you have formatted your DVD to the correct UDF that matches the DVD type that your chip will accept. Here is a list of the UDF formats you will require for each format:

CD-R: UDF 1.51
CD-RW: UDF 1.51
CD-MRW: UDF 1.51
DVD-R: UDF 2.01
DVD-RW: UDF 2.01
DVD+R: UDF 2.01
DVD+RW: UDF 3.01
DVD-RAM: UDF 1.02

You MUST format your DVD in the corresponding UDF that your Chip reads. After it's formatted in the correct UDF, you can then proceed to burn the image on. It's most likely that Nero decided on it's own, what UDF to use and it turned out the UDF it used wasn't accepted by your Chip.