How many clients do you have in your environment?
Assuming that your site is setup properly..(Site boundaries are usually the biggest issue.), I would look at the client SMS logs. These are located in the C:\Winnt\MS\LOGS directory or C:\Windows\MS\Logs dir [depending on client OS]
There are many, many log files here...
The most common type of problem is another remote control agent already being installed on the client machine. For example, I was assigned the task of converting an environment from Intel LANDESK to Microsoft's SMS 2.0. (Landesk is very simlilar to SMS...but made by Intel...) Anyway, I found out very early in the project that if the LANDESK client was installed on the client machines, the SMS remote control agent would fail to install. You see, SMS searches for other remote control software on the client machine before allow the Remote Control agent to install.
Another reason you might have a problem with a client installation (only on NT) is caused by having the SERVER SERVICE disabled. Enable the SERVER SERVICE on the client and then try to install the client softare. This should work.
Anyway, hope this helps...provide more details an maybe we can figure something out.
Later...