I am getting CastInvalid Error Message . I verified all the datatypes . It looks good. I dont know where this error is pointing.

You don't need the CAST. You can simply have the following:

a!forEach(
    items: local!productInfo,
    expression: 'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information'(
      /* map your attributes from each instance of fv!item to your CDT attributes */
    )
  )

Note: if you want to use CAST (which is valid) you need to lose the () suffix from your type! statement i.e.

a!forEach(
    items: local!productInfo,
    expression: cast(
      'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information',
      {
        /* map your attributes from fv!item to your CDT attributes here*/
      }
    )
  )

This is because the instruction type!'<myType>'() is a function to create an instance of your CDT, whereas type!'<myType' is a reference to the type number, and CAST requires the type number of a type not an instance of the type.

Note: if you want to use CAST (which is valid) you need to lose the () suffix from your type! statement i.e.

a!forEach(
    items: local!productInfo,
    expression: cast(
      'type!{urn:com:appian:types:COSELM}COSELM_coselm_eox_information',
      {
        /* map your attributes from fv!item to your CDT attributes here*/
      }
    )
  )

This is because the instruction type!'<myType>'() is a function to create an instance of your CDT, whereas type!'<myType' is a reference to the type number, and CAST requires the type number of a type not an instance of the type.

Good Catch. I missed it.

Yup, just need to be aware that if you let Appian auto-complete your type! statement it will add the () function suffix. It's caught me out in the past...

Yeah. Learned from mistakes. I never forget.. I was breaking my head all looks good why it was failing. then after remove this "()" it fixed the issue. Anyway i learned two things.. We can cast using cast function else using type function to cast directly. 

Thanks again :) for your prompt response. Appian community is fast in responding the queries. Exploring Appian..