language support

When I trying to install regional language in ubuntu 11.04 displaying error report like this , What is this ?

installArchives() failed: perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
 LANGUAGE = (unset),
 LC_ALL = (unset),
 LANG = "en_IN.ISO8859-1"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
 LANGUAGE = (unset),
 LC_ALL = (unset),
 LANG = "en_IN.ISO8859-1"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
 LANGUAGE = (unset),
 LC_ALL = (unset),
 LANG = "en_IN.ISO8859-1"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
(Reading database ...
(Reading database ... 5%%
(Reading database ... 10%%
(Reading database ... 15%%
(Reading database ... 20%%
(Reading database ... 25%%
(Reading database ... 30%%
(Reading database ... 35%%
(Reading database ... 40%%
(Reading database ... 45%%
(Reading database ... 50%%
(Reading database ... 55%%
(Reading database ... 60%%
(Reading database ... 65%%
(Reading database ... 70%%
(Reading database ... 75%%
(Reading database ... 80%%
(Reading database ... 85%%
(Reading database ... 90%%
(Reading database ... 95%%
(Reading database ... 100%%
(Reading database ... 425799 files and directories currently installed.)
Unpacking kde-l10n-ml (from .../kde-l10n-ml_4%%3a4.5.95-0ubuntu1_all.deb) ...
dpkg: error processing /var/cache/apt/archives/kde-l10n-ml_4%%3a4.5.95-0ubuntu1_all.deb (--unpack):
 trying to overwrite '/usr/share/kde4/apps/klettres/ml/sounds.xml', which is also in package klettres-its-data 4:4.4.7-0ubuntu1
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/kde-l10n-ml_4%%3a4.5.95-0ubuntu1_all.deb