Inter MSC HO Failures

I have 2 MSCs, one ericsson and the other Alcatel. I am receiving traces that show high HO Rejections from the Alcatel site into the ericsson site but not the other way around. The sites are 1st tier nbrs. The message is “Ho rejection due to lack of radio resources” from the ericsson site. The actual handover fail rate is low. No appearent HW issue, congestion, interference, etc. Tried nbr optimization, DT, cch additions and also no help. Any thoughts that may be causing this?

Thanks