Synttax for opening report with where clause

[Monoceros]

I don't seem to get the right syntax for opening a report with only the records where the field Reference equals UD :

DoComd.OpenReport "rptCosts", acViewPreview, , Reference= "UD"

What's wrong with the syntax ?

 

[Ranman256]

'strings must have quotes
DoComd.OpenReport "rptCosts", acViewPreview,"[fieldname]='UD'"
or
DoComd.OpenReport "rptCosts", acViewPreview,"[fieldname]='" & txtString & "'"

numbers
DoComd.OpenReport "rptCosts", acViewPreview,"[fieldname]=" & txtNum

 

[Monoceros]

Thank you.