# NullReferenceException when tracking

**URL:** <https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354>\
**Category:** WinForms\
**Created:** [April 15, 2009, 2:42pm UTC](https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354 "2009-04-15T14:42:09Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Kimberly](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/f4b2a3/32.png) [@Kimberly](https://community.thinkgeo.com/u/Kimberly)\
**Post date:** [April 15, 2009, 2:42pm UTC](https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354/1 "2009-04-15T14:42:09Z")

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Good&nbsp;Afternoon,

I&nbsp;came&nbsp;across&nbsp;this&nbsp;behavior&nbsp;and&nbsp;maybe&nbsp;there's&nbsp;something&nbsp;I&nbsp;need&nbsp;to&nbsp;catch,&nbsp;but&nbsp;I&nbsp;can't&nbsp;figure&nbsp;it&nbsp;out.&nbsp;After&nbsp;the&nbsp;user&nbsp;has&nbsp;turned&nbsp;on&nbsp;TrackMode&nbsp;(set&nbsp;it&nbsp;to&nbsp;Polygon,&nbsp;to&nbsp;be&nbsp;complete),&nbsp;if&nbsp;he&nbsp;immediately&nbsp;double-clicks,&nbsp;the&nbsp;app&nbsp;blows&nbsp;up&nbsp;with&nbsp;a&nbsp;NullReferenceException.&nbsp;I&nbsp;have&nbsp;set&nbsp;break&nbsp;points&nbsp;in&nbsp;my&nbsp;methods&nbsp;that&nbsp;capture&nbsp;the&nbsp;Track&nbsp;Shape&nbsp;ending&nbsp;and&nbsp;they&nbsp;are&nbsp;never&nbsp;reached.&nbsp;Break&nbsp;points&nbsp;in&nbsp;MapClick&nbsp;and&nbsp;MouseDoubleClick&nbsp;events&nbsp;are&nbsp;not&nbsp;reached&nbsp;either.

If&nbsp;there&nbsp;was&nbsp;some&nbsp;way&nbsp;I&nbsp;could&nbsp;capture&nbsp;this&nbsp;and&nbsp;alert&nbsp;the&nbsp;user&nbsp;that&nbsp;would&nbsp;be&nbsp;great.

(If&nbsp;they&nbsp;double&nbsp;click&nbsp;after&nbsp;clicking&nbsp;to&nbsp;add&nbsp;the&nbsp;first&nbsp;point,&nbsp;this&nbsp;exception&nbsp;doesn't&nbsp;happen.)

Any&nbsp;advice&nbsp;would&nbsp;be&nbsp;great!

Kimberly

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**Author:** ![Lee](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/l/bc8723/32.png) [@Lee](https://community.thinkgeo.com/u/Lee)\
**Post date:** [April 16, 2009, 3:23am UTC](https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354/2 "2009-04-16T03:23:18Z")

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Kimberly,&nbsp;  
&nbsp;&nbsp;  
&nbsp;We&nbsp;couldn’t&nbsp;recreate&nbsp;it&nbsp;in&nbsp;V3.0.199,&nbsp;could&nbsp;you&nbsp;please&nbsp;confirm&nbsp;you&nbsp;are&nbsp;using&nbsp;the&nbsp;latest&nbsp;version?&nbsp;We&nbsp;tested&nbsp;it&nbsp;on&nbsp;the&nbsp;sample&nbsp;Getting&nbsp;Started\Track&nbsp;and&nbsp;Edit&nbsp;Shape,&nbsp;it&nbsp;works&nbsp;well.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Thanks,&nbsp;  
&nbsp;ThinkGeo&nbsp;Support&nbsp;

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**Author:** ![Kimberly](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/k/f4b2a3/32.png) [@Kimberly](https://community.thinkgeo.com/u/Kimberly)\
**Post date:** [April 16, 2009, 2:13pm UTC](https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354/3 "2009-04-16T14:13:20Z")

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It&nbsp;is&nbsp;a&nbsp;problem&nbsp;with&nbsp;the&nbsp;version.&nbsp;I&nbsp;am&nbsp;using&nbsp;3.0.255.0,&nbsp;which&nbsp;I&nbsp;downloaded&nbsp;as&nbsp;a&nbsp;fix&nbsp;in&nbsp;relation&nbsp;to&nbsp;the&nbsp;discussion&nbsp;forum&nbsp;post&nbsp;regarding&nbsp;an&nbsp;event&nbsp;on&nbsp;Track&nbsp;Shape&nbsp;Completion.

[gis.thinkgeo.com/Support/Dis...fault.aspx](http://gis.thinkgeo.com/Support/DiscussionForums/tabid/143/aff/21/aft/5271/afv/topic/Default.aspx)

I&nbsp;went&nbsp;back&nbsp;to&nbsp;the&nbsp;old&nbsp;version&nbsp;(and&nbsp;commented&nbsp;out&nbsp;the&nbsp;parts&nbsp;of&nbsp;the&nbsp;code&nbsp;that&nbsp;broke)&nbsp;and&nbsp;I&nbsp;don't&nbsp;seem&nbsp;to&nbsp;have&nbsp;the&nbsp;issue&nbsp;with&nbsp;the&nbsp;3.0.199&nbsp;version&nbsp;of&nbsp;the&nbsp;code.

Thanks!

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**Author:** ![Lee](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/l/bc8723/32.png) [@Lee](https://community.thinkgeo.com/u/Lee)\
**Post date:** [April 20, 2009, 4:53am UTC](https://community.thinkgeo.com/t/nullreferenceexception-when-tracking/354/4 "2009-04-20T04:53:49Z")

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Kimberly,&nbsp;  
&nbsp;&nbsp;  
&nbsp;This&nbsp;is&nbsp;a&nbsp;bug&nbsp;in&nbsp;version&nbsp;3.0.255&nbsp;when&nbsp;we&nbsp;do&nbsp;the&nbsp;enhancements&nbsp;on&nbsp;tracking&nbsp;shapes.&nbsp;We&nbsp;suggest&nbsp;you&nbsp;to&nbsp;turn&nbsp;back&nbsp;to&nbsp;version&nbsp;3.0.199,&nbsp;it&nbsp;works&nbsp;fine&nbsp;in&nbsp;your&nbsp;case.&nbsp;Please&nbsp;wait&nbsp;for&nbsp;the&nbsp;upcoming&nbsp;version,&nbsp;which&nbsp;will&nbsp;fix&nbsp;these&nbsp;bugs&nbsp;and&nbsp;enhance&nbsp;the&nbsp;track&nbsp;shape&nbsp;functionality.&nbsp;Sorry&nbsp;for&nbsp;the&nbsp;inconvenience&nbsp;for&nbsp;now.&nbsp;  
&nbsp;&nbsp;  
&nbsp;Thanks,&nbsp;  
&nbsp;ThinkGeo&nbsp;Support