Problem gluing PVC DWV pipes

Howdy;

  I have a problem that I have never encountered before. I have set up my DWV system with a dry fit so the plumbing inspector could look at it before i glued it. I numbered ever part, and made 2 marks on each piece so they would line up exactly once they were glued. Now comes the problem. Once I started putting them together with glue some of the pieces acted as if they had expanded. I have done it this way in the past, and had no problem, but this time it seems like each piece adds to the overall length so when I get to the final connection it too far off to connect, but too close to add another piece. Any ideas?  I use the cleaner/primer, and glue recommended by the pipe manufacturer, and have never bought the cheap versions of anything. It is frustrating as heck. My health only lets me work for a few hours at a time, then it takes a day or two before I can start up again, I hate wasting time redoing something I've already done. Any help will be greatly appreciated. Thank You in advance.

I'm NOT a plumber, but could you have primed, and then glued your pipe and fittings WITHOUT making sure the fittings were all BOTTOMED OUT?  What I mean:  You clean/prime the fittings, then apply the adhesive to both parts, then attach the fitting to the pipe.  When you attach the fitting, did you make sure the fitting and pipe were pressed together until they bottomed out?  NO GAP inside?  It's a quick thing to press on the fitting when the adhesive starts "grabbing".

Just an idea here.  A PRO will most likely have the correct answer.

Like I stated, I'm NOT a plumber in any way, most of the Professional have FORGOTTEN more than I'll ever know!

I made a mark around the pipe at each fitting for depth. They all went back together to their marks. That's why I'm baffled. They fit before. Were marked, and then primed, and glued, then put back exactly as they were. It would seem that there would be no way to mess it up. However having been doing DIY projects for a long time nothing really surprises me anymore.

This can be very precise work so you may have to look at how much glue you're using. You may not think it makes a difference, but the glue does take up space. Not a lot, but maybe enough to be the cause of your problem? Just a thought. 

After you glue the pvc you need to hole them together for a few seconds(20), because the pipe actually slips away. When you glue the pipe put it together and let go you will see what i mean.

oops-hold

Well, I am no professional plumber either but here are my 2-cents worth. I think glue works the same way when being used for any material/product at all. Thus, you need to do it the exact same way like you would when you glue cloth or paper or anything together. You need to wait for awhile after applying the glue and let them actually stick together. Else, the 2 sides might just slip away and that could have caused the "expansion" of length. On the other hand, you could also make longer "marks" so that when the "expansion" occurs, they will go back to the desired correct length that you initially require.