The block diagram uses an Invoke Node to call a method on an object, for example, a VI or an ActiveX control. Unfortunately, the parameter types for this method have changed since you wired the Invoke Node, and LabVIEW does not know what you want to do with the existing wires. LabVIEW indicates this by dimming the Invoke Node. You can find the Invoke Node by clicking the Show Error button in the Error list window.
If you want LabVIEW to attempt to re-wire the Invoke Node for you, right-click the node and select Relink to Invoke Node from the shortcut menu. When LabVIEW is finished re-wiring, the Invoke Node appears in its normal, darker colors.
Otherwise, delete the Invoke Node from the block diagram, place a new node, select the proper method, and wire the parameters.