Which media are you using ?? There are two common causes for power calibration errors.
1. Low Quality Media
At the start of each burn the drive will burn to a small section the the disc to adjust the laser power for the media being used. Low quality media is inconsistent and will frequently give hit or miss results during the power calibration. AN32, CMC and Moser Baer are common low quality media.
Keep in mind that many of the brands of media aren't actually made by the company selling them. To find out who actually manufactured the media you can use DVD Identifier.
The only recourse for power calibration errors with low quality media is to update the firmware for your drive and hope it works. Here's a link to the best firmware page to be found:
2.Your Burner Is Dying
This one is self-explanatory.
If you're using quality media, your firmware is up to date and you're still recieving power calibration errors then your drive is most likely gone or defective. It can read cds but can't burn.