T-SQL (SS2K8) :: Trying To Use Substring (charindex) To Remove Start Of A String

Looking at a trace table and trying to remove all the "erroneous" bits in a string e.g the declares etc so I can purely get to proc names.

An example string

declare @p2 varchar(10) set @p2=NULL exec sp_proc @Code='TF',@TypeCode=@p2 output select @p2

I've tried

select top 5000 textdata,substring(textdata,charindex('exec',textdata)+5,charindex('@',textdata)-1)
from trace_table
where TextData like '%sp_%'
and TextData like '%declare%'

And it fails dismally...