Lookup date field with only year, day and month in SSRS

I'm trying to write an expression where i need to lookup a date value from another sharepoint list. It works well when I only wants to get the value, but when I try to use some date function, like day,month or year I get this error:
The Value expression for the textrun 'Textbox7.Paragraphs[0].TextRuns[2]' has an incorrect number of parameters for the function 'Lookup'.

This is the expression I was using test it,  with the above error message:
=Lookup(Fields!cth_VMID.Value,Fields!cth_VMID.Value,Year(Fields!cth_Date.Value, "Datasetb"))