Cline to other Cline segment Airgap

Hi,

I need one help can any one please help me out from this.

The selected Cline alone has to check the air gap of every cline segment present in the board in that the input value will get by run time. if the airgap value is lesser than input value the cline segment want to be highlight. I'll tried but I shows error can anyone please re correct it.

E- *Error* greaterp: can't handle (4 > nil)

procedure(checkcseg()
axlClearSelSet()
axlSetFindFilter(?enabled `("NOALL" "CLINES") ?onButtons `("CLINES"))
clineschk = axlGetSelSet(axlSelect(?prompt "Select Clines by pick or window."))
if(clineschk then
axlClearSelSet()
axlSetFindFilter(?enabled `("NOALL" "CLINESEGS") ?onButtons `("CLINESEGS"))
clinesegchk = axlGetSelSet(axlAddSelectAll())
val = atoi(axlUIPrompt("Enter the Max Airgap value :"))
if(clinesegchk then
foreach(cln_db clineschk
foreach(csg clinesegchk
_AirGap = lastelem(axlAirGap(cln_db csg csg->layer) )
if(val > _AirGap  then
axlHighlightObject(csg)
print(csg ->xy)
printf("found")
)
)
)
)
)