Following is my sample.sh in /usr/local/bin/

#!/bin/sh
mkdir -p /Volumes/folder
mount -t afp -o rw afp://user:password@server_name/folder_name /Volumes/folder

Following is my com.apple.sample.plist in /Library/LaunchAgents/

 ?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>Label</key>
        <string>com.apple.sample</string>
        <key>ProgramArguments</key>
        <array>
    <string>/usr/local/bin/sample.sh</string>
        </array>
        <key>RunAtLoad</key>
        <true/>
</dict>
</plist>

Where as when I am able to run sample.sh independently and is working fine.

Also I have tried using launchd.conf as

mkdir -p /Volumes/folder
mount -t afp -o rw afp://user:[email protected]/testsuites /Volumes/folder

Still not working.