Taxes done 1/23/19. Transmitted and accepted . Have not received refund. Called IRS and they stated there is an error in return. How is that possible?

Did they say what the error was?

"Accepted" did not mean your return was done correctly--it meant it was done enough for the IRS to accept it for processing. You may have entered something incorrectly or omitted income, etc. If they need information from you they will request the information in writing.  What does it say on the IRS site?

https://www.irs.gov/refunds