Dear Sander,
Your suggestions helped me a lot. As I have mentioned the in ECC there is business function activated. So I found that the table is MATERIALID contains the both 18 and 40 char material codes. Now I have done the datasource enhancement for Material_attr with the field MATNR_EXT which has 40 char. The data is pulling correctly into BI and created one custom IO with the 40 char. and selected conversion routine as MATNL then loaded into the 0Material. Till here it is working fine but the issue comes in Bex analyzer that when I use this field into my report the value is coming as "#" whereas in IO it is loaded correctly.
Please find the below screenshots and suggest valuable suggestion because I am just one step to behind to finish this issue.
Material Master IO:
Bex Analyzer:
Regards,
Abhishek Jain