That means your data has a space after it. If you don't want to "purify" your data, then you can modify TroutTrap2's code this way...
=TRIM(A1&"."&B1)
Now, if the above does not work, then that would mean your space is actually a non-breaking space (ASCII 160) which could come from copying data from the web. If that is the case, then try this formula instead...
=SUBSTITUTE(A1&"."&B1,CHAR(160),"")