Remote commands problem using RSH & Rexec

I have enabled the RSH and Rexec command in my HP-UX server but when i try to send any command to the server it returns Execute Permission Denied except commands like ls-l

C:\rsh xxx.xxx.xxx.xxx -l mpac mxpkill 12

the mxpkill command work when I log to the server using telnet with the same user mpac

help me please I know you're Expert Users:b: