Game Development Visual Studio 2013

Question

i am currently making a running game using window form in visual studio 2013 c# 

i am having trouble when i'm trying to move my obstacle 

here is my code and i manually generate picbox one by one  

i tried to move it with timer and with .Left properties but it seem the width of the picbox increased instead of the left distance

i tried to use .Location.X properties but i got the same result , the width increased instead of the location

 

can someone help me????would really apreciate any kind of solution or advice

 

thanks