A problem with the SynEdit,.Who can help me?

[pkkj]

I am using the SynEdit Control to buiilding an IDE.It like Lazarus.
But when I try to seek the ERROR LINE in the program in the SynEdit.But I find that it can goto the correct line,but it can't draw the correct line in red color.It can only draw the top line at the editor.
How can I solve this problem?
I use the function from the SynEditor:

SynEditor.InvalidateLine(fCurrentLine);

[CCRDude]

To fill lines in special colors, I use the SpecialLineColors event. It's parameters are quite self-explaining