"The curtain in your room is blue."
Translation:Η κουρτίνα του δωματίου σου είναι μπλε.
If you gave the exact same answer but was not accepted, please file a bug report here https://support.duolingo.com/hc/en-us/requests/new. Forum moderators and course contributors have no control over such things and Duolingo staff should be alerted to this.
Bear in mind that answers with a capital letter that looks identical but has been typed in a different language keyboard are not accepted, e.g. Η (Gr) vs H (English).