Daughter says she doesn't want to come to my house anymore

My 13 year old told her mom she doesn't want to come to my place for her custody weeks. Said she misses her friends and wants to stay with her mom. This is breaking me. I don't know what I did wrong. We get along okay when she's here but she's pretty quiet. My ex obviously isn't encouraging her to want to come see me. How do I fix this without looking desperate or making it worse?