diff --git a/doc/source/conf.py b/doc/source/conf.py
index ca1ac74..f2d1463 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -14,7 +14,6 @@
 
 import datetime
 import os
-import re
 import sys
 
 from pbr import version as pbr_ver
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index ddfc90e..f24ca5f 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -10,7 +10,7 @@ There are two ways to install and run VMTP tool. Users of VMTP should use regula
 PyPI based Installation
 -----------------------
 
-PyPI (The Python Package Index) is the offical repository for software in Python. It holds lots of packages, and the installation is relatively easy in only 2 steps.
+PyPI (The Python Package Index) is the official repository for software in Python. It holds lots of packages, and the installation is relatively easy in only 2 steps.
 
 Step 1
 ^^^^^^
@@ -42,6 +42,12 @@ Create a virtual environment for Python, and install VMTP::
     $ pip install vmtp
     $ vmtp -h
 
+**Note:** "A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them." It is optional but recommended. We could use::
+
+    $ sudo pip install vmtp
+
+instead if isolation among multiple Python projects is not needed.
+
 
 .. _git_installation:
 
diff --git a/doc/source/usage.rst b/doc/source/usage.rst
index 7143c8a..3d44fe8 100644
--- a/doc/source/usage.rst
+++ b/doc/source/usage.rst
@@ -20,9 +20,7 @@ VMTP Usage
                    [--vnic-type <direct|macvtap|normal>] [-d] [-v]
                    [--stop-on-error] [--vm-image-url <url_to_image>]
                    [--test-description <test_description>]
-    
-    OpenStack VM Throughput V2.1.4
-    
+
     optional arguments:
       -h, --help            show this help message and exit
       -c <config_file>, --config <config_file>
diff --git a/vmtp/vmtp.py b/vmtp/vmtp.py
index 4e37c7a..c0e4a5f 100755
--- a/vmtp/vmtp.py
+++ b/vmtp/vmtp.py
@@ -666,7 +666,7 @@ def main():
         return dest_config
 
     logging.basicConfig()
-    parser = argparse.ArgumentParser(description='OpenStack VM Throughput ' + __version__)
+    parser = argparse.ArgumentParser()
 
     parser.add_argument('-c', '--config', dest='config',
                         action='store',
@@ -974,14 +974,17 @@ def main():
     vmtp_instance = None
 
     cred = credentials.Credentials(opts.rc, opts.pwd, opts.no_env)
-    if cred.rc_auth_url:
-        if config.debug:
-            print 'Using ' + cred.rc_auth_url
-        vmtp_instance = VmtpTest(config, cred)
-        for item in native_tp_results:
-            vmtp_instance.rescol.add_flow_result(item)
-        vmtp_instance.run()
-        vmtp_net = vmtp_instance.net
+    if not cred.rc_auth_url:
+        print 'Error: Cannot read the credentials of the cloud. '
+        sys.exit(1)
+
+    if config.debug:
+        print 'Using ' + cred.rc_auth_url
+    vmtp_instance = VmtpTest(config, cred)
+    for item in native_tp_results:
+        vmtp_instance.rescol.add_flow_result(item)
+    vmtp_instance.run()
+    vmtp_net = vmtp_instance.net
 
     # Retrieve controller information if requested
     # controller node ssh access to collect metadata for the run.