Product ID is represeneted in a couple of different formats in SCM – and hence in EWM.
Table /SAPAPO/MATKEY contains a MATID (Internal Number (UID) for Product) which consists of 22 characters which is a mixture of upper and lower case letters as well as digits.
On the other hand in EWM most tables and references refer to materials via hexidecimal numbers with length 16 (32 characters).
Function module /SCMB/MDL_GUID_CONVERT can be used to convert between these two formats.