Column Visibility Expression

I'm trying to show a column only if a certain parameter contains a certain string of characters. So far I've got it working if the parameter is equal to the string of characters by doing

=IIF (Parameters!Param1.Value = "String1", False, True)

but I would like it to work if the Param1.Value contains "String1" ... I tried

=IIF (Parameters!Param1.Value like "%String1%", False, True)

but it doesn't work. Any suggestions?

TIA

Using the InStr function works!|||Hide the item if the string is found:
=IIf(InStr(Parameters!Param1.Value, "string") <> 0 , True, False)
or
=IIf(InStr(Parameters!Param1.Value, "string") = 0 , False, True)

Show item if string is found:
=IIf(InStr(Parameters!Param1.Value, "string") <> 0 , False, True)
or
=IIf(InStr(Parameters!Param1.Value, "string") = 0 , True, False)
|||

Hello,

I'm using the exact same syntax as given below and I get the error message

=IIf(InStr(Parameters!Measure.Value, "string") <> 0 , False,True)

Error : The Hidden expression for the table 'table1' contains an error: Conversion from Type 'Object()' to type 'String' is not valid

I'm not sure what is wrong here..

Any help would be appreciated!!

Thanks,