Cufflinks error: coercing to Unicode

[axgraf]

Hi all,

I was running Cufflinks (cufflinks v1.0.3) without any problem up to now. But today I encountered the following error:

Error running cufflinks. coercing to Unicode: need string or buffer, NoneType found

I might be wrong but I think it could be the BAM file!? I think that cufflinks gets confused by the reference sequence, wich has Roman numerals in it. If I run cufflinks with BAM files from other reference sequences (e.g. chr1, chr2, ..., chrX) it doesn't complain at all. But I am acutally not sure.
Has anybody encountered the same problem?

Here is a part of the BAM file:
6:1:3100:7855:Y 16 2micron 5443 255 78M * 0 0 ....
6:1:3832:7022:Y 0 2micron 5448 255 78M * 0 0 ....
6:1:3601:13275:Y 16 2micron 5471 255 78M * 0 ....
6:1:2150:10018:Y 16 2micron 5541 255 78M * 0 ....
6:1:2683:4385:Y 0 chrI 35820 255 78M * 0 0 ....
6:1:3238:6491:Y 0 chrVI 41486 255 78M * 0 0 ....

Thank you for your help