I created a path by combining two different paths and this has apparently resulted in the nodes being out of order. Therefore, when I fill the path, the fill is not correct:
How can I fix this problem?
The problem is that some of the nodes are not connected, in other words there are two nodes instead of one and they are not joined.
To fix this, zoom in closely on the nodes causing the problem and select them with the node tool. Then choose "join nodes" from the node editing toolbar.
If you still have a problem, select the whole path and choose "break apart" from the path menu. Then selectively recombine each subpath one by one, making sure that all subpaths are connected by a single node.