I always and underline the word ALWAYS use the same techinique to make a search in a table and put the result in a textbox:

From the textbox in the doubleclick event I call the form which make the search
- do form SearchForm to lcRetval
if !empty(lcRetval)
this.value = lcRetval
.......

well yesterday i get the error DataType mismatch.
i look at the line of code which gave me the error and LISTEN !!:
=SEEK(THIS.VALUE,'MyTable','MyIdx')
i check the value in this.value and it was a charachter type, checked the idx expression and it was a character type.

Any Ideas ?
Moreover, doing the same thing a second time it works ok and it carry on working fine .....
Thank you
Alessio