SInce you are facing problem with more than one client it is better to assaign a package with all required features
Do as follows
Create a new custom Client Install Feature Set
Open the Symantec Endpoint Protection Manager console.
On the Admin tab, under Tasks, click Install Packages.
The current default client installation packages appear on the right.
Under View Install Packages, click Client Install Feature Sets.
Under Tasks, click Add Client Install Feature Sets.
Specify the name you would like the Client Install Feature Set to have.
Give the Client Install Feature Set a description.
Select the components you want to include in the install package from the following list:
AntiVirus and AntiSpyware Protection
AntiVirus Email Protection
Microsoft Outlook Scanner(don't forget to select this)
Lotus Notes Scanner
POP3/SMTP Scanner
Proactive Threat Protection
Proactive Threat Scan
Application and Device Control
Network Threat Protection
Network Threat Protection
When you are finished, click OK.
To assain the packages
Click Admin > Install Packages.
In the lower-left pane, under Tasks, click Upgrade Groups with Package.
In the Welcome to the Upgrade Groups Wizard panel, click Next.
In the Select Client Install Package panel, all existing client packages are listed in the drop down box. Select one of the following:
Symantec Endpoint Protection <appropriate version>.
Click Next.
In the Specify Groups panel, check one or more groups that contain the client computers to be migrated, then click Next.
In the Package Upgrade Settings panel, check Download client from the management server.
Click Upgrade Settings.
In the Add Client Install Package dialog box, on the General tab, remove keep existing client features , then configure a schedule for when to migrate the client computers.Then you select the client feature which you create in the earlier steps. Under the Notification tab, specify a message to display to users during the migration.
If the clients in the group run a version of Symantec Endpoint Protection previous to MR2, turn off scheduling. Scheduling is on by default when a new client install package is added to a group. If scheduling is turned on, the upgrade fails. To turn off scheduling, in the Add Client Install Package dialog box, uncheck Upgrade Schedule.
For details about settings on these tabs, click Help.
Click OK.
In the Upgrade Groups Wizard dialog box, click Next.
In the Upgrade Groups Wizard Complete panel, click Finish.