I have been burning an SVCD disk with Nero 5.5.8.0

I made two MPEG2 files with TMPGEnc using the normal template rate 2520kb/s

I usually burn these file with Nero using the "try to fit to disk size" encoding bit rate.
But I just tried the "user defined" which lets you elect a rate. I selected 255KB/s out the the selections (there was no 2520) All PAL

With the "fit disk size" I can fast forward x2, x4,x8 on my standalone DVD and have no problems

but with the "user defined" using Fast forward on the DVD often ends with a jump between files or locked in a loop in a file.

Any ideas on why this happens??