Acrobat Pro Preflight B+W failure

Hello all,

I hope people don't mind me asking this here.
We use Acrobat Pro every day to convert to cmyk and more importantly convert to B+W.

About 3-4 times a year we suffer preflight failure and acrobat pro produces b+w files that have some elements of colour in them and this causes a colour click charge on our press if we print duplex with color one side and b+w back.

Adobe are not much help, heres a copy of my message on their support forum:

"Take a colour pdf, open in acrobat pro, select preflight - convert to black and white for digital printing and usually it calls up 2 errors:

"The pdf doc uses features that require at least acrobat 5"

"compressed object streams used"

The 2 above errors should not be a problem anyway, we have seen these errors before but still had a successful conversion to a Black and White plate.

Every time we use preflight b+w now we get plates which have some colour element to them and our digital press then charges us for a colour print.

To try and help you, this problem occurs 3-4 times per year and usually we fix it by re-installing acrobat pro but this time it does not fix the issue.

We have been paying for acrobat pro for years now, we upgrade every year and the same thing happens every year."

If anyone here knows of a fix please let me know.

Thanks

 

Registration marks on your Doc

Kinda late to point that out but, when that happens it's the registration marks most of the time..
(Crosses, Trim Marks, etc have a spot color named "Registration" which contains all colors on the job even if b+w it will have CMY)