Apple’s anticipated iPhone 6 announcement next month could reportedly be delayed due to supply chain issues.

According to Reuters, problems with the screens necessitated a redesign. Assembly was delayed during parts of June and July.

“Now, Apple had been trying to make the new models as thin as possible, but the screen and a newer design for the iPhone 6 was not bright enough. So, they had to go back to the drawing board and rework it,” said FBN’s Jo Ling Kent, citing the Reuters report.

Analysts are expecting Apple to unveil two iPhone 6 models: One with a 4.7-inch screen, and another with a larger 5.5-inch screen. Apple has scheduled a media event for September 9, at which many assume the company will introduce the new phones. It is unclear whether the supply issues will delay the event.

Apple screen suppliers Japan Display, Inc., Sharp Corp., and LG Display Co. were not available for comment on the design issues. Apple's stock is up over 26% year-to-date, widely outpacing the broad S&P 500.