While opening projects from one version in another can give problems, you might like to make a copy of your PRE10 project file and just try opening it in PRE11 and see if it works. If you are trying to take a project from one machine to another then try using the project archiver as this will collect the project file and all the project assets together in one folder you can copy across and restore.
If it doesn't work then you can Share> Computer on your PRE10 computer to a DV file and bring that into a PRE11 project.
But you say that you are only trying to do this to actually BURN the DVD. What problems are you having with burning in PRE10? Maybe we can help you with that. For example if it is an issue with different PC's one of which doesn't have a burner, you can burn your PRE10 project to a folder, copy the folder to the machine with the burner and use the free ImgBurn to actually burn the DVD. No need to involve PRE11 at all.
Insanity is hereditary, you get it from your children.
Welcome to the forum.
In addition to Neale's suggestions, remember that the trial version of PrE will add a watermark to the output - I do not think you will want a "created in Premiere Elements Trial" overlay Title on your DVD.
Maybe an unnecessary precaution, but I will mention it nonetheless as a "just in case"....
Classically, if you create a project.prel in one version of Premiere Elements and then decide to edit or export it in a later version, you cannot open the later version edited project.prel in the earlier version again. I have seen that when dealing with two purchased different versions of Premiere Elements. But I have not worked with the situation of a purchased Premiere Elements 10 and a tryout Premiere Elements 11.
In spite of that classical statement, recent versions of purchased Premere Elements appear to contradict that finding. I can work back and forth between two purchased programs in the "opening the project" aspects of the matter. But, there can be some unexpected/unwanted consequences along the way.
Remember the watermark on your DVD-VIDEO on DVD disc created in the tryout Premiere Elements 11 cannot be removed, even after you purchase a serial number for the Premiere Elements 11. You can remove the watermark in Premiere Elements 11 project.prel files after you purchase a serial number/program. Further, you cannot remove the watermark from a file derived from the Timeline exported to a file saved on the computer hard drive even after the serial number purchase.