I see 2 issue's:
1 - This seems to be done on a (open)Solaris box. My example is based on GNU sed, make sure to use that one if possible. It might be in /usr/local/bin and/or called gsed.
2 - The example given by me doesn't make in-place changes, add the -i flag:
sed -i '9 r new_txt' PAT_MDQD_EMINI.test
If you use a sed version that does not include the -i option, do the following:
sed '9 r new_txt' PAT_MDQD_EMINI.test > /tmp/PME.test
mv /tmp/PME.test > PAT_MDQD_EMINI.test
BTW: GNU versions of packages for Solaris can be downloaded from here: Sunfreeware.com