what do you mean by HO Problem ? You could not possibly be LESS specific…
For multiband networks, you muist ensure that:
1/ SI2 and SI5 will broadcast the “other-band” neighbours
2/ MS will report “other band” neighbours
3/ handover cause “better neighbour cell” is working also for target cells which are “other band” cells.
You have to find which parametrs are controlling those 3 points in your system.. If it were ALU, I could help.