Transition to a DCH not be completed

Hi all,
I would like to ask about drops in umts due to “Channel Switching-Transition to a DCH connection has been initiated but can not be completed”
Which is the most common reason for having it. I know that it happens when Ue tried to perform a channel switching and it drops but, how can we overcome that issue.
IF you can help me with some parameters or advises i will appreciate that
Thanks in advance,
Carlos