SEALY, Texas -

Thieves ruined a birthday girl's wish and her parents didn't have any clue until their daughter opened the gift.

Bobbie Linden said she went to the Walmart store in Sealy, Texas to buy her daughter Courtney an iPad for her 15th birthday. She immediately took it home and gave it to her.

Courtney opened up the box and there was not an iPad inside. She said she found four Walmart notebooks instead. Courtney said she thought her parents were playing a joke on her.

"Once I saw my mom's face, I realized this is probably more serious," Courtney said.

Linden said she rushed back to the store. Only about 20 minutes had passed between the time the iPad was purchased and the time she returned.

Linden said managers told her that there was nothing they could do.

Linden called police, who told her it was a civil matter. Her husband then went to the district's attorney's office to file a complaint. He was told to consider stopping the payment.

Walmart's corporate office said they looked into the matter and determined that someone took the iPad out of the box, sealed it back up and returned it with the notebooks inside.

"Unfortunately, it resulted in an innocent customer falling victim to a scam artist's greed," Walmart spokeswoman Dianna Gee said.

Walmart officials said they would refund the family's money and give Courtney a free iPad.

Walmart said they're working with Sealy police to find out who stole the iPad.

"We have reviewed our surveillance video to see if we can find out who is responsible for this," Gee said. "We have shared that information with local law enforcement in hopes that whoever is behind this is held responsible for their selfish acts."