created an iDVD slide show, burned to dvd but it won't play in my Sony dvd player

Does your Sony player accept other home-made DVDs?

How did you create the slideshow?

To simply create a slide show in iDVD 7 onwards from images in iPhoto or stored in other places on your hard disk or a connected server, look here:

https://support.apple.com/kb/PH5489?viewlocale=en_US&locale=en_US

Preparing images for iDVD slideshows:

https://discussions.apple.com/content/attachment/581055040

If you are using the Photos app for Yosemite, look here:

https://help.apple.com/photos/mac/1.0/?lang=en#/phtae8c6d40

Try again following this workflow to help assure the best qualty video DVD:

Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.

To check the encoding mount the disk image, launch DVD Player and play it. If it plays OK with DVD Player the encoding is good.

Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.