Help - Still Trying To Insert 255+ Chars Into Text

How do you insert more than 255 characters into a text field? or am I using READTEXT and DATALENGTH incorrectly?

I am trying to concatenate two 255 varchar strings. Both do have 255 characters of data.
I want to insert the concatenated strings into a field define as a text data type.
if I try to ' insert into tempTbl(textFieldDataType) values (@text1+@text2) it appears only the @text1 is inserted.
I have been told the data is really there, but I can only read the 256 position + with READTEXT.

DECLARE @textptr varbinary(16)
select @textptr = (select TEXTPTR(textFieldDataType) from tempTbl where pktempTbl = 33)
READTEXT tempTbl.textFieldDataType @textPtr 255 10

This should have read 10 text positions after the 255th position. However, I get msg
Msg 7124, Level 16, State 1
The offset and length specified in the READTEXT command is greater than the actual data length of 255.

If I use the datalength function, it appears to confirm that @text2 was never inserted

declare @length int
select @length = (select datalength(textFieldDataTypet) from tempTbl where pktempTbl = 33)
select @length

@length is returned as 255