Solaris 10u9 cant open ports

Hello there,

im have a portserver 2 connected to a m3000 which is running solaris 10u9.
After creating the ports using drpadmin im having trouble accessing some of them.

root# tip /dev/cua/a001 
tip: /dev/cua/a001: Resource temporarily unavailable all ports busy

root#/home/spsy> fuser /dev/cua/a001

root# tip /dev/cua/a002

#root# fuser /dev/cua/a002

root# tip /dev/cua/a003

root# fuser /dev/cua/a003
/dev/cua/a003:     5278o

root# ps -fea | grep 5278
    spsy  5278     1   0 17:03:31 ?           0:00 /home/s/sys/seri
    root 29798 29787   0 12:21:45 pts/3       0:00 grep 5278

The strange thing is that accessing /dev/cua/a001 worked for a few times.