Function and Variable declaration with out an 'As' clause

I get a message - "Function without an 'As' clause" for HMAC_MD5 and "Variable declaration without an 'As' clause" for Key and Value.  But the code works.  But the messages still exists.  Is there a way to fix this to avoid the messages?
Function HMAC_MD5(ByVal Key, ByVal Value)
 
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