Calculated field issue

=IF(SEARCH("";[Relative URL]);("http://i-tec.signin.no"&[Relative URL]);(IF(SEARCH(" ";[Relative URL]);"http://i-tec.signin.no"&REPLACE([Relative URL];SEARCH(" ";[Relative URL]);1;"%20"))))
Hi, I used this formula for my calculated field. But the second part is not working. I need to replace space with %20. if there is no space i dont need the the replacement.
The formula working for individual conditions. 
This works for the space
IF(SEARCH(" ";[Relative URL]);"http://i-tec.signin.no"&REPLACE([Relative URL];SEARCH(" ";[Relative URL]);1;"%20"))
This work for no space.
=IF(SEARCH("";[Relative URL]);"http://i-tec.signin.no"&[Relative URL])
But when I join both of this first conditions works. Pls help me