Loft Feature - Guide curves

Hello all,
I'm still trying to get better with the loft feature, half the time i try to use some curves to guide the loft feature i do something wrong and the feature fails. Inside the attachment you can find my most recent attempt to figure it out but i still have no idea  about whats wrong with it. I got two similar profiles parallel to each other with same amount of corners and some spline curves in between connecting these two profiles from corner to corner. Loft feature works just fine as long as i dont select any guide curves. Can someone explain to me what i am doing wrong when it comes to guide curves?

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