unable to create a folder in the /var/custom

[shankarjai2525]

I'm unable to create a folder in the /var/custom folder in the base image store/ibmcorp/db2_developer_c:11.1.4.4-x86_64

This is the error I get when I try to build the image
Step 2/4 : RUN mkdir /var/custom/DViewWE
---> Running in aaf9b4845192
mkdir: cannot create directory '/var/custom/DViewWE': No such file or directory

Here is the dockerFile
FROM store/ibmcorp/db2_developer_c:11.1.4.4-x86_64

RUN mkdir /var/custom/DViewWE

COPY CreateDViewWEDB.sql /var/custom
RUN chmod a+x /var/custom/CreateDViewWEDB.sql

Need help.