Problem with Omniquad Instant Remote Control

I Have a problem accessing workgroup computer using an open license Omniquad Instant Remote Control 2.2.9 it always replies "access is denied on the remote machine".
I get firewall off, remove any antivirus or firewall programs, enabled network access to the remote computer "windows XP pro", tried remote desktop connection with settings "user, password, IP" and I also find the same problem using goverlan. Should I have a domain for these programs? and Are there any other recommended programs? Thanks in advance.