Regarding Max flow problem ( Ford-Fulkerson Algorithm) I'm looking for the max flow in this graph but something is going wrong. 

First I take the path : 1-2-4-6. So the flow ie $F=1$
Then : 1-3-2-5-4-6 and the flow updates to $F=2+1=3$
If i take the path : 1-3-5-6 my flow is $F=3+2=5$ 
And the graph is disconnected now. I can't  reach 6 starting in 1. I know the maximum flow should be 6 but I think the algorithm stops when there's not path joining the source and the target.
What's the extra condition I'm missing? How can i find the maximum flow?

Hint
So you just proved (by counterexample) that maximum flow is not the same as maximal flow.
To construct the maximum flow, look at the graph and note that minimum cut of size $6$ occurs in $\{(2,4),(2,5),(3,5)\}$, so all of these have to be used to maximum capacity, and in your flow they are not.
If you need more hints, ask questions...
