recordset filter by length of a string colum

Question

This is in VB.NET.

I have a requirement to display only the values of a column where the length of the column value is greater than 1.

I used the below approach.

objRecordSet.Filter = "LEN(FIRSTNAME) > 1"

But it is not working. Can you please suggest me if there is any issue in the above code or if there is any other alternative.

Thanks Vaas