Formula to view records

Hi,
I am having a report which takes a parameter to view records based on the parameter value passed to it.

I need to check the length of the parameter, if the length of the parameter value is "4", it should compare the parameter value with one field value, if the length is more than 4, then it should compare the value with another field and shoe me the records.

I have made the formula, but it doesn't show records, where as there are records in the table.

how could i do that ? Is anybody there, who could help me in that?

Thanks in advance.

Regards

DeepakIf len(parameter)=4 then
--do some work
else
--do some other work

Do you want to do this from Front end application?