Dsum with mutiple variables

What's wrong with this statement?

strSQL = "DSum('share_pct', 'CoInsurer', 'Policy_No = ' & Chr$(34) & " StrPolicy & Chr$(34) & ' AND Version_No = ' & Chr$(34) & StrVer & Chr$(34))"

I get a compile error ' Expected end of statement with strpolicy highlighted. '

Desperate to resolve this any help appreciated

Thanks Colin