Difference bwtween BME and DTT in sample buffer for WB after IP - (Mar/21/2007 )

what is the difference between BME and DTT in the sample buffer?

I am using BME as a reducing agent for the western blot and it works fine.

However, if I do 'WB after IP', the proteins are sitting on the top of the gel.
(I see the very thick band on the film corresponding to the top of the gel)

someone told me to use DTT instead of BME but he didn't tell me what is the difference between them.

since we don't have DTT in stock, I like to know what is the advantage to use DTT in SB before purchase it.

I am also willing to take any advise regarding " the protein sitting on the top of the gel" problem

Thank you.