Push Traffic in multiband NW

Hi all (ZTE Vender)
I applied the following modification to push traffic from 900 to 1800 but it still 900 carrying most of traffic :
Cell Neighbor cell Ncell layer RxLevMin HOMarginPBGT HOMarginRxLev HOMarginRxQual
900 Cell_900 Cell_1800 Undefined 25 26 28 26
1800 Cell_1800 Cell_1800 Same layer 25 26 28 26

900 Cell_900 Cell_900 Same layer 15 30 30 30
1800 Cell_1800 Cell_900 Undefined 15 36 28 26

please help me to improve the network..
thanks