Well I'm trying the same thing here and I get a "#error" in the field using the following expression, what am I doing wrong...:

=Mid(Fields!storageDimensionCode.Value,InStr(Fields!storageDimensionCode.Value," "),(InStr(Fields!storageDimensionCode.Value," ") - InStr(Fields!storageDimensionCode.Value,"H")))

Thank you all for posting.... 😎